indexing
	description: "[
		EiffelVision table. Invisible container that allows
		unlimited number of other widgets to be packed inside it.
		A table controls the children's location and size
		automatically."
	]"
	legal: "See notice at end of class."
	status: "See notice at end of class."
	date: "$Date: 2006-01-22 18:25:44 -0800 (Sun, 22 Jan 2006) $"
	revision: "$Revision: 56675 $"

class interface
	EV_TABLE

create 
	default_create
			-- Standard creation procedure.
			-- (from EV_ANY)
		require -- from  ANY
			True
		ensure then -- from EV_ANY
			is_coupled: implementation /= Void
			is_initialized: is_initialized
			default_create_called_set: default_create_called
			is_in_default_state: is_in_default_state

feature -- Access

	accept_cursor: EV_POINTER_STYLE
			-- `Result' is cursor displayed when the screen pointer is over a
			-- target that accepts pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			result_not_void: Result /= Void
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.accept_cursor

	actual_drop_target_agent: FUNCTION [ANY, TUPLE [INTEGER_32, INTEGER_32], EV_ABSTRACT_PICK_AND_DROPABLE]
			-- Overrides default drop target on a certain position.
			-- If `Void', `Current' will use the default drop target.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.actual_drop_target_agent

	background_color: EV_COLOR
			-- Color displayed behind foreground features.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_COLORIZABLE
			bridge_ok: Result.is_equal (implementation.background_color)

	background_pixmap: EV_PIXMAP
			-- `Result' is pixmap displayed on background of `Current'.
			-- It is tessellated and fills whole of `Current'.
			-- (from EV_CONTAINER)
		require -- from EV_PIXMAPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PIXMAPABLE
			bridge_ok: (Result = Void and implementation.background_pixmap = Void) or Result.is_equal (implementation.background_pixmap)

	columns: INTEGER_32
			-- Number of columns in `Current'.
		require
			not_destroyed: not is_destroyed

	data: ANY
			-- Arbitrary user data may be stored here.
			-- (from EV_ANY)

	default_key_processing_handler: PREDICATE [ANY, TUPLE [EV_KEY]] assign set_default_key_processing_handler
			-- Agent used to determine whether the default key processing should occur for Current.
			-- If agent returns True then default key processing continues as normal, False prevents
			-- default key processing from occurring.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.default_key_processing_handler

	deny_cursor: EV_POINTER_STYLE
			-- `Result' is cursor displayed when the screen pointer is over a
			-- target that does not accept pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			result_not_void: Result /= Void
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.deny_cursor

	first: like item
			-- Item at first position
			-- (from CHAIN)
		require -- from CHAIN
			not_empty: not is_empty

	foreground_color: EV_COLOR
			-- Color of foreground features like text.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_COLORIZABLE
			bridge_ok: Result.is_equal (implementation.foreground_color)

	generating_type: STRING_8
			-- Name of current object's generating type
			-- (type of which it is a direct instance)
			-- (from ANY)

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)

	has_recursive (an_item: like item): BOOLEAN
			-- Does structure include `an_item' or
			-- does any structure recursively included by structure,
			-- include `an_item'.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed

	help_context: FUNCTION [ANY, TUPLE, EV_HELP_CONTEXT]
			-- Agent that evaluates to help context sent to help engine when help is requested
			-- (from EV_HELP_CONTEXTABLE)
		require -- from EV_HELP_CONTEXTABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_HELP_CONTEXTABLE
			bridge_ok: Result = implementation.help_context

	i_th alias "[]" (i: INTEGER_32): like item assign put_i_th
			-- Item at `i'-th position
			-- Was declared in CHAIN as synonym of infix "@".
			-- (from CHAIN)
		require -- from TABLE
			valid_key: valid_index (i)

	frozen id_object (an_id: INTEGER_32): IDENTIFIED
			-- Object associated with `an_id' (void if no such object)
			-- (from IDENTIFIED)
		ensure -- from IDENTIFIED
			consistent: Result = Void or else Result.object_id = an_id

	index_of (v: like item; i: INTEGER_32): INTEGER_32
			-- Index of `i'-th occurrence of item identical to `v'.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- 0 if none.
			-- (from CHAIN)
		require -- from LINEAR
			positive_occurrences: i > 0
		ensure -- from LINEAR
			non_negative_result: Result >= 0

	item: EV_WIDGET
			-- Current item.
			-- (from EV_CONTAINER)
		require -- from TRAVERSABLE
			not_off: not off
		require -- from ACTIVE
			readable: readable
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			readable: readable
		ensure -- from EV_CONTAINER
			bridge_ok: Result = implementation.item

	item_at_position (a_column, a_row: INTEGER_32): EV_WIDGET
			-- Widget at coordinates (`row', `column').
		require
			not_destroyed: not is_destroyed
			valid_row: (1 <= a_row) and (a_row <= rows)
			valid_column: (1 <= a_column) and (a_column <= columns)

	item_column_position (widget: EV_WIDGET): INTEGER_32
			-- `Result' is column coordinate of `widget'.
		require
			not_destroyed: not is_destroyed
			widget_contained: has (widget)
		ensure
			result_valid: Result > 0 and Result <= columns - item_column_span (widget) + 1

	item_column_span (widget: EV_WIDGET): INTEGER_32
			-- `Result' is number of columns taken by `widget'.
		require
			not_destroyed: not is_destroyed
			widget_contained: has (widget)
		ensure
			result_valid: Result > 0 and Result <= columns - item_column_position (widget) + 1

	item_row_position (widget: EV_WIDGET): INTEGER_32
			-- `Result' is row coordinate of `widget'.
		require
			not_destroyed: not is_destroyed
			widget_contained: has (widget)
		ensure
			result_valid: Result > 0 and Result <= rows - item_row_span (widget) + 1

	item_row_span (widget: EV_WIDGET): INTEGER_32
			-- `Result' is number of rows taken by `widget'.
		require
			not_destroyed: not is_destroyed
			widget_contained: has (widget)
		ensure
			result_valid: Result > 0 and Result <= rows - item_row_position (widget) + 1

	last: like item
			-- Item at last position
			-- (from CHAIN)
		require -- from CHAIN
			not_empty: not is_empty

	frozen object_id: INTEGER_32
			-- Unique for current object in any given session
			-- (from IDENTIFIED)
		ensure -- from IDENTIFIED
			valid_id: id_object (Result) = Current

	sequential_occurrences (v: like item): INTEGER_32
			-- Number of times `v' appears.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from LINEAR)
		require -- from  BAG
			True
		ensure -- from BAG
			non_negative_occurrences: Result >= 0

	parent: EV_CONTAINER
			-- Contains `Current'.
			-- (from EV_WIDGET)
		require -- from EV_CONTAINABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_WIDGET
			bridge_ok: Result = implementation.parent

	pebble: ANY
			-- Data to be transported by pick and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble

	pebble_function: FUNCTION [ANY, TUPLE, ANY]
			-- Returns data to be transported by pick and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_function

	pebble_positioning_enabled: BOOLEAN
			-- If `True' then pick and drop start coordinates are
			-- pebble_x_position, pebble_y_position.
			-- If `False' then pick and drop start coordinates are
			-- the pointer coordinates.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_positioning_enabled

	pebble_x_position: INTEGER_32
			-- Initial x position for pick and drop relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_x_position

	pebble_y_position: INTEGER_32
			-- Initial y position for pick and drop relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_y_position

	pointer_position: EV_COORDINATE
			-- Position of the screen pointer relative to `Current'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			is_show_requested: is_show_requested

	pointer_style: EV_POINTER_STYLE
			-- Cursor displayed when pointer is over this widget.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	real_target: EV_DOCKABLE_TARGET
			-- `Result' is target used during a dockable transport if
			-- mouse pointer is above `Current'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.real_target

	rows: INTEGER_32
			-- Number of rows in `Current'.
		require
			not_destroyed: not is_destroyed

	target_name: STRING_GENERAL
			-- Optional textual name describing `Current' pick and drop hole.
			-- (from EV_ABSTRACT_PICK_AND_DROPABLE)

	infix "@" (i: INTEGER_32): like item assign put_i_th
			-- Item at `i'-th position
			-- Was declared in CHAIN as synonym of i_th.
			-- (from CHAIN)
		require -- from TABLE
			valid_key: valid_index (i)
	
feature -- Measurement

	client_height: INTEGER_32
			-- Height of the area available to children in pixels. 
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
		ensure -- from EV_CONTAINER
			bridge_ok: Result = implementation.client_height

	client_width: INTEGER_32
			-- Width of the area available to children in pixels. 
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
		ensure -- from EV_CONTAINER
			bridge_ok: Result = implementation.client_width

	index_set: INTEGER_INTERVAL
			-- Range of acceptable indexes
			-- (from CHAIN)
		require -- from  INDEXABLE
			True
		ensure -- from INDEXABLE
			not_void: Result /= Void
		ensure then -- from CHAIN
			count_definition: Result.count = count

	occurrences (v: like item): INTEGER_32
			-- Number of times `v' appears.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from CHAIN)
		require -- from  BAG
			True
		require -- from  LINEAR
			True
		ensure -- from BAG
			non_negative_occurrences: Result >= 0

	screen_x: INTEGER_32
			-- Horizontal offset relative to left of screen in pixels.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.screen_x

	screen_y: INTEGER_32
			-- Vertical offset relative to top of screen in pixels.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.screen_y
	
feature -- Comparison

	frozen deep_equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		ensure -- from ANY
			shallow_implies_deep: standard_equal (some, other) implies Result
			both_or_none_void: (some = Void) implies (Result = (other = Void))
			same_type: (Result and (some /= Void)) implies some.same_type (other)
			symmetric: Result implies deep_equal (other, some)

	frozen equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

	is_equal (other: like Current): BOOLEAN
			-- Is `other' attached to an object considered
			-- equal to current object?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			symmetric: Result implies other.is_equal (Current)
			consistent: standard_is_equal (other) implies Result

	frozen standard_equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached to
			-- field-by-field identical objects of the same type?
			-- Always uses default object comparison criterion.
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

	frozen standard_is_equal (other: like Current): BOOLEAN
			-- Is `other' attached to an object of the same type
			-- as current object, and field-by-field identical to it?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
	
feature -- Status report

	area_clear (a_column, a_row, column_span, row_span: INTEGER_32): BOOLEAN
			-- Are the cells represented by parameters free of widgets?
		require
			not_destroyed: not is_destroyed
			table_wide_enough: a_column + (column_span - 1) <= columns
			table_tall_enough: a_row + (row_span - 1) <= rows

	area_clear_excluding_widget (v: EV_WIDGET; a_column, a_row, column_span, row_span: INTEGER_32): BOOLEAN
			-- Are the cells represented by parameters free of widgets? Excludes cells
			-- filled by `v'.
		require
			not_destroyed: not is_destroyed
			table_wide_enough: a_column + (column_span - 1) <= columns
			table_tall_enough: a_row + (row_span - 1) <= rows

	border_width: INTEGER_32
			-- Spacing between edge of `Current' and outside edge items,
			-- in pixels.
		require
			not_destroyed: not is_destroyed
		ensure
			result_non_negative: Result >= 0

	column_clear (a_column: INTEGER_32): BOOLEAN
			-- Is column `a_column' free of widgets?
		require
			not_destroyed: not is_destroyed
			a_column_positive: a_column >= 1
			a_column_in_table: a_column <= columns

	column_spacing: INTEGER_32
			-- Spacing between two consecutive columns, in pixels.
		require
			not_destroyed: not is_destroyed
		ensure
			result_non_negative: Result >= 0

	columns_resizable_to (a_column: INTEGER_32): BOOLEAN
			-- May the column count be resized to `a_column'?
		require
			not_destroyed: not is_destroyed
			a_column_positive: a_column >= 1

	conforms_to (other: ANY): BOOLEAN
			-- Does type of current object conform to type
			-- of `other' (as per Eiffel: The Language, chapter 13)?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void

	duplicate (n: INTEGER_32): like Current
			-- Copy of sub-chain beginning at current position
			-- and having min (`n', `from_here') items,
			-- where `from_here' is the number of items
			-- at or to the right of current position.
			-- This is not implementable in Vision2 as a widget may
			-- only be parented in one container at once. Hence, the
			-- `Void' `Result'.
		require -- from CHAIN
			not_off_unless_after: off implies after
			valid_subchain: n >= 0

	exhausted: BOOLEAN
			-- Has structure been completely explored?
			-- (from LINEAR)
		ensure -- from LINEAR
			exhausted_when_off: off implies Result

	extendible: BOOLEAN
			-- May new items be added?

	has_capture: BOOLEAN
			-- Does widget have capture?
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.has_capture

	has_focus: BOOLEAN
			-- Does widget have the keyboard focus?
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.has_focus

	is_displayed: BOOLEAN
			-- Is `Current' visible on the screen?
			-- `True' when show requested and parent displayed.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.is_displayed

	is_dockable: BOOLEAN
			-- Is `Current' dockable?
			-- If `True', then `Current' may be dragged
			-- from its current parent. 
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			bridge_ok: Result = implementation.is_dockable

	is_empty: BOOLEAN
			-- Is structure empty?
			-- (from FINITE)
		require -- from  CONTAINER
			True

	is_external_docking_enabled: BOOLEAN
			-- Is `Current' able to be docked into an EV_DOCKABLE_DIALOG
			-- When there is no valid EV_DRAGABLE_TARGET upon completion
			-- of transport?
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			bridge_ok: Result = implementation.is_external_docking_enabled

	is_external_docking_relative: BOOLEAN
			-- Will dockable dialog displayed when `Current' is docked externally
			-- be displayed relative to parent window of `Current'?
			-- Otherwise displayed as a standard window.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			bridge_ok: Result = implementation.is_external_docking_relative

	is_homogeneous: BOOLEAN
			-- Are all items forced to have same dimensions.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.is_homogeneous

	is_inserted (v: EV_WIDGET): BOOLEAN
			-- Has `v' been inserted by the most recent insertion?
			-- (By default, the value returned is equivalent to calling 
			-- `has (v)'. However, descendants might be able to provide more
			-- efficient implementations.)
			-- (from COLLECTION)

	is_sensitive: BOOLEAN
			-- Is object sensitive to user input.
			-- (from EV_SENSITIVE)
		require -- from EV_SENSITIVE
			not_destroyed: not is_destroyed
		ensure -- from EV_SENSITIVE
			bridge_ok: Result = implementation.user_is_sensitive

	is_show_requested: BOOLEAN
			-- Will `Current' be displayed when its parent is?
			-- See also is_displayed.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.is_show_requested

	isfirst: BOOLEAN
			-- Is cursor at first position?
			-- (from CHAIN)
		ensure -- from CHAIN
			valid_position: Result implies not is_empty

	islast: BOOLEAN
			-- Is cursor at last position?
			-- (from CHAIN)
		ensure -- from CHAIN
			valid_position: Result implies not is_empty

	merged_radio_button_groups: ARRAYED_LIST [EV_CONTAINER]
			-- `Result' is all other radio button groups
			-- merged with `Current'. Void if no other containers
			-- are merged.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
		ensure -- from EV_CONTAINER
			not_is_empty: Result /= Void implies not Result.is_empty

	mode_is_drag_and_drop: BOOLEAN
			-- Is the user interface mode drag and drop?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_drag_and_drop

	mode_is_pick_and_drop: BOOLEAN
			-- Is the user interface mode pick and drop?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_pick_and_drop

	mode_is_target_menu: BOOLEAN
			-- Is the user interface mode a pop-up menu of targets?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_target_menu

	object_comparison: BOOLEAN
			-- Must search operations use equal rather than `='
			-- for comparing references? (Default: no, use `='.)
			-- (from CONTAINER)

	off: BOOLEAN
			-- Is there no current item?
			-- (from CHAIN)
		require -- from  TRAVERSABLE
			True

	prunable: BOOLEAN is True
			-- `Current' is always prunable.

	readable: BOOLEAN
			-- Is there a current item that may be read?
			-- (from SEQUENCE)
		require -- from  ACTIVE
			True
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed

	real_source: EV_DOCKABLE_SOURCE
			-- `Result' is source to be dragged
			--  when a docking drag occurs on `Current'.
			-- If `Void', `Current' is dragged.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			bridge_ok: Result = implementation.real_source

	row_clear (a_row: INTEGER_32): BOOLEAN
			-- Is row `a_row' free of widgets?
		require
			not_destroyed: not is_destroyed
			a_row_positive: a_row >= 1
			a_row_in_table: a_row <= rows

	row_spacing: INTEGER_32
			-- Spacing between two consecutive rows, in pixels.
		require
			not_destroyed: not is_destroyed
		ensure
			result_non_negative: Result >= 0

	rows_resizable_to (a_row: INTEGER_32): BOOLEAN
			-- May the row count be resized to `a_row'?
		require
			not_destroyed: not is_destroyed
			a_row_positive: a_row >= 1

	same_type (other: ANY): BOOLEAN
			-- Is type of current object identical to type of `other'?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))

	valid_cursor_index (i: INTEGER_32): BOOLEAN
			-- Is `i' correctly bounded for cursor movement?
			-- (from CHAIN)
		ensure -- from CHAIN
			valid_cursor_index_definition: Result = ((i >= 0) and (i <= count + 1))

	valid_index (i: INTEGER_32): BOOLEAN
			-- Is `i' within allowable bounds?
			-- (from CHAIN)
		require -- from  TABLE
			True
		ensure then -- from INDEXABLE
			only_if_in_index_set: Result implies ((i >= index_set.lower) and (i <= index_set.upper))
		ensure then -- from CHAIN
			valid_index_definition: Result = ((i >= 1) and (i <= count))

	writable: BOOLEAN
			-- Is there a current item that may be modified?
			-- (from SEQUENCE)
		require -- from  ACTIVE
			True
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
	
feature -- Status setting

	center_pointer
			-- Position screen pointer over center of `Current'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	compare_objects
			-- Ensure that future search operations will use equal
			-- rather than `=' for comparing references.
			-- (from CONTAINER)
		require -- from CONTAINER
			changeable_comparison_criterion: changeable_comparison_criterion
		ensure -- from CONTAINER
			object_comparison

	compare_references
			-- Ensure that future search operations will use `='
			-- rather than equal for comparing references.
			-- (from CONTAINER)
		require -- from CONTAINER
			changeable_comparison_criterion: changeable_comparison_criterion
		ensure -- from CONTAINER
			reference_comparison: not object_comparison

	disable_capture
			-- Disable grab of all user input events.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			not_has_capture: not has_capture

	disable_dockable
			-- Ensure `Current' is not dockable.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			not_is_dockable: not is_dockable

	disable_external_docking
			-- Assign `False' to is_external_docking_enabled.
			-- Forbid `Current' to be docked into an EV_DOCKABLE_DIALOG
			-- When there is no valid EV_DRAGABLE_TARGET upon completion
			-- of transport.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			is_dockable: is_dockable
		ensure -- from EV_DOCKABLE_SOURCE
			not_externally_dockable: not is_external_docking_enabled

	disable_external_docking_relative
			-- Assign `False' to is_external_docking_relative, ensuring that
			-- a dockable dialog displayed when `Current' is docked externally
			-- is displayed as a standard window.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			external_docking_enabled: is_external_docking_enabled
		ensure -- from EV_DOCKABLE_SOURCE
			external_docking_not_relative: not is_external_docking_relative

	disable_pebble_positioning
			-- Assign `False' to pebble_positioning_enabled.
			-- The pick and drop will start at the pointer position.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_positioning_updated: not pebble_positioning_enabled

	disable_sensitive
			-- Make object non-sensitive to user input.
			-- (from EV_SENSITIVE)
		require -- from EV_SENSITIVE
			not_destroyed: not is_destroyed
		ensure -- from EV_SENSITIVE
			is_unsensitive: not is_sensitive

	enable_capture
			-- Grab all user input events (mouse and keyboard).
			-- disable_capture must be called to resume normal input handling.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			is_displayed: is_displayed
		ensure -- from EV_WIDGET
			has_capture: has_capture

	enable_dockable
			-- Ensure `Current' is dockable.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			is_dockable: is_dockable

	enable_external_docking
			-- Assign `True' to is_external_docking_enabled.
			-- Allows `Current' to be docked into an EV_DOCKABLE_DIALOG
			-- When there is no valid EV_DRAGABLE_TARGET upon completion
			-- of transport.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			is_dockable: is_dockable
		ensure -- from EV_DOCKABLE_SOURCE
			is_externally_dockable: is_external_docking_enabled

	enable_external_docking_relative
			-- Assign `True' to is_external_docking_relative, ensuring that
			-- a dockable dialog displayed when `Current' is docked externally
			-- is displayed relative to the top level window.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			external_docking_enabled: is_external_docking_enabled
		ensure -- from EV_DOCKABLE_SOURCE
			external_docking_not_relative: is_external_docking_relative

	enable_pebble_positioning
			-- Assign `True' to pebble_positioning_enabled.
			-- Use pebble_x_position and pebble_y_position as the initial coordinates
			-- for the pick and drop in pixels relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_positioning_updated: pebble_positioning_enabled

	enable_sensitive
			-- Make object sensitive to user input.
			-- (from EV_SENSITIVE)
		require -- from EV_SENSITIVE
			not_destroyed: not is_destroyed
		ensure -- from EV_SENSITIVE
			is_sensitive: (parent = Void or parent_is_sensitive) implies is_sensitive

	hide
			-- Request that `Current' not be displayed even when its parent is.
			-- If successful, make is_show_requested `False'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	merge_radio_button_groups (other: EV_CONTAINER)
			-- Merge `Current' radio button group with that of `other'.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			other_not_void: other /= Void

	remove_default_key_processing_handler
			-- Ensure default_key_processing_handler is Void.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			default_key_processing_handler_removed: default_key_processing_handler = Void

	remove_pebble
			-- Make pebble `Void' and pebble_function `Void,
			-- Removing transport.
			-- (from EV_PICK_AND_DROPABLE)
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_removed: pebble = Void and pebble_function = Void

	remove_real_source
			-- Ensure real_source is `Void'.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
		ensure -- from EV_DOCKABLE_SOURCE
			real_source_void: real_source = Void

	remove_real_target
			-- Ensure real_target is `Void'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			real_target_void: real_target = Void

	set_accept_cursor (a_cursor: like accept_cursor)
			-- Set `a_cursor' to be displayed when the screen pointer is over a
			-- target that accepts pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_cursor_not_void: a_cursor /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			accept_cursor_assigned: accept_cursor.is_equal (a_cursor)

	set_actual_drop_target_agent (an_agent: like actual_drop_target_agent)
			-- Assign `an_agent' to actual_drop_target_agent.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			an_agent_not_void: an_agent /= Void
		ensure -- from EV_WIDGET
			assigned: actual_drop_target_agent = an_agent

	set_default_colors
			-- Set foreground and background color to their default values.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed

	set_default_key_processing_handler (a_handler: like default_key_processing_handler)
			-- Assign default_key_processing_handler to `a_handler'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	set_deny_cursor (a_cursor: like deny_cursor)
			-- Set `a_cursor' to be displayed when the screen pointer is not
			-- over a valid target.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_cursor_not_void: a_cursor /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			deny_cursor_assigned: deny_cursor.is_equal (a_cursor)

	set_drag_and_drop_mode
			-- Set user interface mode to drag and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			drag_and_drop_set: mode_is_drag_and_drop

	set_focus
			-- Grab keyboard focus.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			is_displayed: is_displayed
			is_sensitive: is_sensitive

	set_pebble (a_pebble: like pebble)
			-- Assign `a_pebble' to pebble.
			-- Overrides set_pebble_function.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_pebble_not_void: a_pebble /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_assigned: pebble = a_pebble

	set_pebble_function (a_function: FUNCTION [ANY, TUPLE, ANY])
			-- Set `a_function' to compute pebble.
			-- It will be called once each time a pick occurs, the result
			-- will be assigned to pebble for the duration of transport.
			-- When a pick occurs, the pick position in widget coordinates,
			-- <<x, y>> in pixels, is passed.
			-- To handle this data use `a_function' of type
			-- FUNCTION [ANY, TUPLE [INTEGER, INTEGER], ANY] and return the
			-- pebble as a function of x and y.
			-- Overrides set_pebble.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_function_not_void: a_function /= Void
			a_function_takes_two_integer_open_operands: a_function.valid_operands ([1, 1])
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_function_assigned: pebble_function = a_function

	set_pebble_position (a_x, a_y: INTEGER_32)
			-- Set the initial position for pick and drop
			-- Coordinates are in pixels and are relative to position of `Current'.
			-- Pebble_positioning_enabled must be `True' for the position to be used,
			-- use enable_pebble_positioning.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_position_assigned: pebble_x_position = a_x and pebble_y_position = a_y

	set_pick_and_drop_mode
			-- Set user interface mode to pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pick_and_drop_set: mode_is_pick_and_drop

	set_real_source (dockable_source: EV_DOCKABLE_SOURCE)
			-- Assign `dockable_source' to real_source.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			is_dockable: is_dockable
			dockable_source_not_void: dockable_source /= Void
			dockable_source_is_parent_recursive: source_has_current_recursive (dockable_source)
		ensure -- from EV_DOCKABLE_SOURCE
			real_source_assigned: real_source = dockable_source

	set_real_target (a_target: EV_DOCKABLE_TARGET)
			-- Assign `a_target' to real_target.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			target_not_void: a_target /= Void
		ensure -- from EV_WIDGET
			assigned: real_target = a_target

	set_target_menu_mode
			-- Set user interface mode to pop-up menu of targets.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			target_menu_mode_set: mode_is_target_menu

	set_target_name (a_name: STRING_GENERAL)
			-- Assign `a_name' to target_name.
			-- (from EV_ABSTRACT_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_name_not_void: a_name /= Void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			target_name_assigned: a_name /= target_name and a_name.is_equal (target_name)

	show
			-- Request that `Current' be displayed when its parent is.
			-- `True' by default.
			-- If successful, make is_show_requested `True'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	unmerge_radio_button_groups (other: EV_CONTAINER)
			-- Remove `other' from radio button group of `Current'.
			-- If no radio button of `other' was checked before removal
			-- then first radio button contained will be checked.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			other_is_merged: merged_radio_button_groups.has (other)
		ensure -- from EV_CONTAINER
			other_not_merged: other.merged_radio_button_groups = Void
			not_contained_in_this_group: merged_radio_button_groups /= Void implies not merged_radio_button_groups.has (other)
			other_first_radio_button_now_selected: not old other.has_selected_radio_button and old other.has_radio_button implies other.first_radio_button_selected
			original_radio_button_still_selected: old has_selected_radio_button implies has_selected_radio_button
			other_first_radio_button_now_selected: not old has_selected_radio_button and old other.has_radio_button and old merged_radio_button_groups.count = 1 and has_radio_button implies first_radio_button_selected
			other_original_radio_button_still_selected: old other.has_selected_radio_button implies other.has_selected_radio_button
	
feature -- Cursor movement

	finish
			-- Move cursor to last position.
			-- (No effect if empty)
			-- (from CHAIN)
		require -- from  LINEAR
			True
		ensure then -- from CHAIN
			at_last: not is_empty implies islast

	go_i_th (i: INTEGER_32)
			-- Move cursor to `i'-th position.
			-- (from CHAIN)
		require -- from CHAIN
			valid_cursor_index: valid_cursor_index (i)
		ensure -- from CHAIN
			position_expected: index = i

	search (v: like item)
			-- Move to first position (at or after current
			-- position) where item and `v' are equal.
			-- If structure does not include `v' ensure that
			-- exhausted will be true.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from BILINEAR)
		ensure -- from LINEAR
			object_found: (not exhausted and object_comparison) implies equal (v, item)
			item_found: (not exhausted and not object_comparison) implies v = item

	start
			-- Move cursor to first position.
			-- (No effect if empty)
			-- (from CHAIN)
		require -- from  TRAVERSABLE
			True
		ensure then -- from CHAIN
			at_first: not is_empty implies isfirst
	
feature -- Element change

	add (v: EV_WIDGET; a_column, a_row, column_span, row_span: INTEGER_32)
			-- Set the position of the widgets in one-based coordinates. 
			--
			--           1         2
			--     +----------+---------+
			--   1 |xxxxxxxxxxxxxxxxxxxx|
			--     +----------+---------+
			--   2 |          |         |
			--     +----------+---------+
			--
			-- To describe the widget in the table as shown above,
			-- the corresponding coordinates would be (1, 1, 2, 1)
			-- Was declared in EV_TABLE as synonym of put_at_position.
		require
			not_destroyed: not is_destroyed
			v_not_void: v /= Void
			v_not_current: v /= Current
			v_not_contained: not has (v)
			v_parent_void: v.parent = Void
			v_not_parent_of_current: not is_parent_recursive (v)
			v_containable: may_contain (v)
			a_column_positive: a_column >= 1
			a_row_positive: a_row >= 1
			column_span_positive: column_span >= 1
			row_span_positive: row_span >= 1
			table_wide_enough: a_column + (column_span - 1) <= columns
			table_tall_enough: a_row + (row_span - 1) <= rows
			table_area_clear: area_clear (a_column, a_row, column_span, row_span)
		ensure
			item_inserted: has (v)
			count_increased: count = old count + 1
			position_assigned: item_column_position (v) = a_column and item_row_position (v) = a_row
			span_assigned: item_column_span (v) = column_span and item_row_span (v) = row_span

	append (s: SEQUENCE [EV_WIDGET])
			-- Append a copy of `s'.
			-- (from CHAIN)
		require -- from SEQUENCE
			argument_not_void: s /= Void
		ensure -- from SEQUENCE
			new_count: count >= old count

	extend (v: like item)
			-- Ensure that structure includes `v'.
			-- Do not move cursor.
			-- (from EV_CONTAINER)
		require -- from COLLECTION
			extendible: extendible
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			extendible: extendible
			v_not_void: v /= Void
			v_parent_void: v.parent = Void
			v_not_current: v /= Current
			v_not_parent_of_current: not is_parent_recursive (v)
			v_containable: may_contain (v)
		ensure -- from COLLECTION
			item_inserted: is_inserted (v)
		ensure then -- from BAG
			one_more_occurrence: occurrences (v) = old (occurrences (v)) + 1
		ensure -- from EV_CONTAINER
			has_v: has (v)

	fill (other: CONTAINER [EV_WIDGET])
			-- Fill with as many items of `other' as possible.
			-- The representations of `other' and current structure
			-- need not be the same.
			-- (from CHAIN)
		require -- from COLLECTION
			other_not_void: other /= Void
			extendible: extendible

	force (v: like item)
			-- Add `v' to end.
			-- (from SEQUENCE)
		require -- from SEQUENCE
			extendible: extendible
		ensure then -- from SEQUENCE
			new_count: count = old count + 1
			item_inserted: has (v)

	prune (v: EV_WIDGET)
			-- Remove `v' if present. Do not move cursor, except if
			-- cursor was on `v', move to right neighbor.
		require -- from COLLECTION
			prunable: prunable
		ensure then
			not_has_v: not has (v)
			had_item_implies_parent_void: old has (v) implies v.parent = Void
			had_item_implies_count_decreased: old has (v) implies count = old count - 1

	put (v: like item)
			-- Replace item with `v'.
			-- Was declared in EV_CONTAINER as synonym of replace.
			-- (from EV_CONTAINER)
		require -- from COLLECTION
			extendible: extendible
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			writable: writable
			v_not_void: v /= Void
			v_parent_void: v.parent = Void
			v_not_current: v /= Current
			v_not_parent_of_current: not is_parent_recursive (v)
			v_containable: may_contain (v)
		ensure -- from COLLECTION
			item_inserted: is_inserted (v)
		ensure then -- from CHAIN
			same_count: count = old count
		ensure -- from EV_CONTAINER
			has_v: has (v)
			not_has_old_item: not has (old item)

	put_at_position (v: EV_WIDGET; a_column, a_row, column_span, row_span: INTEGER_32)
			-- Set the position of the widgets in one-based coordinates. 
			--
			--           1         2
			--     +----------+---------+
			--   1 |xxxxxxxxxxxxxxxxxxxx|
			--     +----------+---------+
			--   2 |          |         |
			--     +----------+---------+
			--
			-- To describe the widget in the table as shown above,
			-- the corresponding coordinates would be (1, 1, 2, 1)
			-- Was declared in EV_TABLE as synonym of add.
		require
			not_destroyed: not is_destroyed
			v_not_void: v /= Void
			v_not_current: v /= Current
			v_not_contained: not has (v)
			v_parent_void: v.parent = Void
			v_not_parent_of_current: not is_parent_recursive (v)
			v_containable: may_contain (v)
			a_column_positive: a_column >= 1
			a_row_positive: a_row >= 1
			column_span_positive: column_span >= 1
			row_span_positive: row_span >= 1
			table_wide_enough: a_column + (column_span - 1) <= columns
			table_tall_enough: a_row + (row_span - 1) <= rows
			table_area_clear: area_clear (a_column, a_row, column_span, row_span)
		ensure
			item_inserted: has (v)
			count_increased: count = old count + 1
			position_assigned: item_column_position (v) = a_column and item_row_position (v) = a_row
			span_assigned: item_column_span (v) = column_span and item_row_span (v) = row_span

	put_i_th (v: like item; i: INTEGER_32)
			-- Put `v' at `i'-th position.
			-- (from CHAIN)
		require -- from TABLE
			valid_key: valid_index (i)
		ensure then -- from INDEXABLE
			insertion_done: i_th (i) = v

	remove
			-- Remove current item.
		require -- from ACTIVE
			prunable: prunable
			writable: writable

	remove_help_context
			-- Remove key press action associated with `EV_APPLICATION.help_key'.
			-- (from EV_HELP_CONTEXTABLE)
		require -- from EV_HELP_CONTEXTABLE
			not_destroyed: not is_destroyed
			help_context_not_void: help_context /= Void
		ensure -- from EV_HELP_CONTEXTABLE
			no_help_context: help_context = Void

	remove_background_pixmap
			-- Remove image displayed on `Current'.
			-- (from EV_PIXMAPABLE)
		require -- from EV_PIXMAPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PIXMAPABLE
			pixmap_removed: background_pixmap = Void

	replace (v: like item)
			-- Replace item with `v'.
			-- Was declared in EV_CONTAINER as synonym of put.
			-- (from EV_CONTAINER)
		require -- from ACTIVE
			writable: writable
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			writable: writable
			v_not_void: v /= Void
			v_parent_void: v.parent = Void
			v_not_current: v /= Current
			v_not_parent_of_current: not is_parent_recursive (v)
			v_containable: may_contain (v)
		ensure -- from ACTIVE
			item_replaced: item = v
		ensure -- from EV_CONTAINER
			has_v: has (v)
			not_has_old_item: not has (old item)

	set_background_color (a_color: like background_color)
			-- Assign `a_color' to background_color.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
			a_color_not_void: a_color /= Void
		ensure -- from EV_COLORIZABLE
			background_color_assigned: background_color.is_equal (a_color)

	set_data (some_data: like data)
			-- Assign `some_data' to data.
			-- (from EV_ANY)
		require -- from EV_ANY
			not_destroyed: not is_destroyed
		ensure -- from EV_ANY
			data_assigned: data = some_data

	set_foreground_color (a_color: like foreground_color)
			-- Assign `a_color' to foreground_color.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
			a_color_not_void: a_color /= Void
		ensure -- from EV_COLORIZABLE
			foreground_color_assigned: foreground_color.is_equal (a_color)

	set_help_context (an_help_context: like help_context)
			-- Assign `an_help_context' to help_context.
			-- (from EV_HELP_CONTEXTABLE)
		require -- from EV_HELP_CONTEXTABLE
			not_destroyed: not is_destroyed
			an_help_context_not_void: an_help_context /= Void
		ensure -- from EV_HELP_CONTEXTABLE
			help_context_assigned: help_context.is_equal (an_help_context)

	set_minimum_height (a_minimum_height: INTEGER_32)
			-- Set `a_minimum_height' in pixels to minimum_height.
			-- If height is less than `a_minimum_height', resize.
			-- From now, minimum_height is fixed and will not be changed
			-- dynamically by the application anymore.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_minimum_height_positive: a_minimum_height >= 0
		ensure -- from EV_WIDGET
			minimum_height_assigned: minimum_height = a_minimum_height
			minimum_height_set_by_user_set: minimum_height_set_by_user

	set_minimum_size (a_minimum_width, a_minimum_height: INTEGER_32)
			-- Assign `a_minimum_height' to minimum_height
			-- and `a_minimum_width' to minimum_width in pixels.
			-- If width or height is less than minimum size, resize.
			-- From now, minimum size is fixed and will not be changed
			-- dynamically by the application anymore.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_minimum_width_positive: a_minimum_width >= 0
			a_minimum_height_positive: a_minimum_height >= 0
		ensure -- from EV_WIDGET
			minimum_width_assigned: minimum_width = a_minimum_width
			minimum_height_assigned: minimum_height = a_minimum_height
			minimum_height_set_by_user_set: minimum_height_set_by_user
			minimum_width_set_by_user_set: minimum_width_set_by_user

	set_minimum_width (a_minimum_width: INTEGER_32)
			-- Assign `a_minimum_width' in pixels to minimum_width.
			-- If width is less than `a_minimum_width', resize.
			-- From now, minimum_width is fixed and will not be changed
			-- dynamically by the application anymore.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_minimum_width_positive: a_minimum_width >= 0
		ensure -- from EV_WIDGET
			minimum_width_assigned: minimum_width = a_minimum_width
			minimum_width_set_by_user_set: minimum_width_set_by_user

	set_background_pixmap (a_pixmap: EV_PIXMAP)
			-- Display image of `a_pixmap' on `Current'.
			-- Image of `pixmap' will be a copy of `a_pixmap'.
			-- Image may be scaled in some descendents, i.e EV_TREE_ITEM
			-- See EV_TREE.set_pixmaps_size.
			-- (from EV_PIXMAPABLE)
		require -- from EV_PIXMAPABLE
			not_destroyed: not is_destroyed
			pixmap_not_void: a_pixmap /= Void

	set_pointer_style (a_cursor: like pointer_style)
			-- Assign `a_cursor' to pointer_style.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_cursor_not_void: a_cursor /= Void
		ensure -- from EV_WIDGET
			pointer_style_assigned: pointer_style.is_equal (a_cursor)
	
feature -- Removal

	prune_all (v: like item)
			-- Remove all occurrences of `v'; go off.
			-- (from SEQUENCE)
		require -- from COLLECTION
			prunable: prunable
		ensure -- from COLLECTION
			no_more_occurrences: not has (v)
	
feature -- Transformation

	swap (i: INTEGER_32)
			-- Exchange item at `i'-th position with item
			-- at cursor position.
			-- (from CHAIN)
		require -- from CHAIN
			not_off: not off
			valid_index: valid_index (i)
		ensure -- from CHAIN
			swapped_to_item: item = old i_th (i)
			swapped_from_item: i_th (i) = old item
	
feature -- Conversion

	linear_representation: LINEAR [EV_WIDGET]
			-- Representation as a linear structure
			-- (from LINEAR)
		require -- from  CONTAINER
			True
	
feature -- Duplication

	copy (other: like Current)
			-- Update current object using fields of object attached
			-- to `other', so as to yield equal objects.
			-- (from EV_ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_equal: is_equal (other)

	frozen deep_copy (other: like Current)
			-- Effect equivalent to that of:
			--		copy (`other' . deep_twin)
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)

	frozen deep_twin: like Current
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		ensure -- from ANY
			deep_equal: deep_equal (Current, Result)

	frozen standard_copy (other: like Current)
			-- Copy every field of `other' onto corresponding field
			-- of current object.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)

	frozen standard_twin: like Current
			-- New object field-by-field identical to `other'.
			-- Always uses default copying semantics.
			-- (from ANY)
		ensure -- from ANY
			standard_twin_not_void: Result /= Void
			equal: standard_equal (Result, Current)

	frozen twin: like Current
			-- New object equal to `Current'
			-- twin calls copy; to change copying/twining semantics, redefine copy.
			-- (from ANY)
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result.is_equal (Current)
	
feature -- Basic operations

	frozen default: like Current
			-- Default value of object's type
			-- (from ANY)

	frozen default_pointer: POINTER
			-- Default value of type `POINTER'
			-- (Avoid the need to write `p'.default for
			-- some `p' of type `POINTER'.)
			-- (from ANY)

	default_rescue
			-- Process exception for routines with no Rescue clause.
			-- (Default: do nothing.)
			-- (from ANY)

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)

	propagate_background_color
			-- Propagate background_color recursively, to all children.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
		ensure -- from EV_CONTAINER
			background_color_propagated: background_color_propagated

	propagate_foreground_color
			-- Propagate foreground_color recursively, to all children.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
		ensure -- from EV_CONTAINER
			foreground_color_propagated: foreground_color_propagated

	refresh_now
			-- Force an immediate redraw of `Current'.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
	
feature -- Implementation

	changeable_comparison_criterion: BOOLEAN is False
			-- May object_comparison be changed?
			-- (Answer: no by default.)
			-- (from EV_CONTAINER)
	
feature -- Command

	destroy
			-- Destroy underlying native toolkit object.
			-- Render `Current' unusable.
			-- (from EV_ANY)
		ensure -- from EV_ANY
			is_destroyed: is_destroyed
	
feature -- Contract support

	is_in_default_state: BOOLEAN
			-- Is `Current' in its default state.
		require -- from  EV_ANY
			True

	is_parent_recursive (a_widget: EV_WIDGET): BOOLEAN
			-- Is `a_widget' parent, or recursivly, parent of parent.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed

	may_contain (v: EV_WIDGET): BOOLEAN
			-- May `v' be inserted in `Current'.
			-- Instances of EV_WINDOW may not be inserted
			-- in a container even though they are widgets.
			-- (from EV_CONTAINER)

	parent_of_source_allows_docking: BOOLEAN
			-- Does parent of source to be transported
			-- allow current to be dragged out? (See real_source)
			-- Not all Vision2 containers are currently supported by this
			-- mechanism, only descendents of EV_DOCKABLE_TARGET
			-- are supported.
			-- (from EV_DOCKABLE_SOURCE)

	source_has_current_recursive (source: EV_DOCKABLE_SOURCE): BOOLEAN
			-- Does `source' recursively contain `Current'?
			-- As seen by parenting structure.
			-- (from EV_DOCKABLE_SOURCE)
		require -- from EV_DOCKABLE_SOURCE
			not_destroyed: not is_destroyed
			source_not_void: source /= Void
	
feature -- Event handling

	conforming_pick_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when a pebble that fits here is picked.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= Void

	dock_ended_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed after a dock completes from `Current'.
			-- Either to a dockable target or a dockable dialog.
			-- (from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES)
		ensure -- from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES
			not_void: Result /= Void

	dock_started_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when a dockable source is dragged.
			-- (from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES)
		ensure -- from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES
			not_void: Result /= Void

	drop_actions: EV_PND_ACTION_SEQUENCE
			-- Actions to be performed when a pebble is dropped here.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= Void

	focus_in_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when keyboard focus is gained.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	focus_out_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when keyboard focus is lost.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	key_press_actions: EV_KEY_ACTION_SEQUENCE
			-- Actions to be performed when a keyboard key is pressed.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	key_press_string_actions: EV_KEY_STRING_ACTION_SEQUENCE
			-- Actions to be performed when a keyboard press generates a displayable character.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	key_release_actions: EV_KEY_ACTION_SEQUENCE
			-- Actions to be performed when a keyboard key is released.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	mouse_wheel_actions: EV_INTEGER_ACTION_SEQUENCE
			-- Actions to be performed when mouse wheel is rotated.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pick_actions: EV_PND_START_ACTION_SEQUENCE
			-- Actions to be performed when pebble is picked up.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= Void

	pick_ended_actions: EV_PND_FINISHED_ACTION_SEQUENCE
			-- Actions to be performed when a transport from `Current' ends.
			-- If transport completed successfully, then event data
			-- is target. If cancelled, then event data is Void.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_button_press_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer button is pressed.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_button_release_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer button is released.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_double_press_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer is double clicked.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_enter_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer enters widget.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_leave_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer leaves widget.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	pointer_motion_actions: EV_POINTER_MOTION_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer moves.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		require -- from  EV_ABSTRACT_PICK_AND_DROPABLE
			True
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void

	resize_actions: EV_GEOMETRY_ACTION_SEQUENCE
			-- Actions to be performed when size changes.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= Void
	
feature -- Iteration

	do_all (action: PROCEDURE [ANY, TUPLE [EV_WIDGET]])
			-- Apply `action' to every item.
			-- Semantics not guaranteed if `action' changes the structure;
			-- in such a case, apply iterator to clone of structure instead.
			-- (from LINEAR)
		require -- from TRAVERSABLE
			action_exists: action /= Void

	do_if (action: PROCEDURE [ANY, TUPLE [EV_WIDGET]]; test: FUNCTION [ANY, TUPLE [EV_WIDGET], BOOLEAN])
			-- Apply `action' to every item that satisfies `test'.
			-- Semantics not guaranteed if `action' or `test' changes the structure;
			-- in such a case, apply iterator to clone of structure instead.
			-- (from LINEAR)
		require -- from TRAVERSABLE
			action_exists: action /= Void
			test_exits: test /= Void

	for_all (test: FUNCTION [ANY, TUPLE [EV_WIDGET], BOOLEAN]): BOOLEAN
			-- Is `test' true for all items?
			-- Semantics not guaranteed if `test' changes the structure;
			-- in such a case, apply iterator to clone of structure instead.
			-- (from LINEAR)
		require -- from TRAVERSABLE
			test_exits: test /= Void
		ensure then -- from LINEAR
			empty: is_empty implies Result

	there_exists (test: FUNCTION [ANY, TUPLE [EV_WIDGET], BOOLEAN]): BOOLEAN
			-- Is `test' true for at least one item?
			-- Semantics not guaranteed if `test' changes the structure;
			-- in such a case, apply iterator to clone of structure instead.
			-- (from LINEAR)
		require -- from TRAVERSABLE
			test_exits: test /= Void
	
feature -- Iteration.

	after: BOOLEAN
			-- Is there no valid position to the right of current one?

	back
			-- Move to previous position.
		require -- from BILINEAR
			not_before: not before

	before: BOOLEAN
			-- Is there no valid position to the left of current one?

	count: INTEGER_32
			-- Number of widgets contained in `Current'.
		require -- from  FINITE
			True
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed

	cursor: CURSOR
			-- Current cursor position.
		require -- from  CURSOR_STRUCTURE
			True
		ensure -- from CURSOR_STRUCTURE
			cursor_not_void: Result /= Void
		ensure then
			bridge_ok: Result.is_equal (implementation.cursor)

	forth
			-- Move to next position; if no next position,
			-- ensure that exhausted will be true.
		require -- from LINEAR
			not_after: not after

	full: BOOLEAN
			-- Is structure filled to capacity?

	go_to (p: CURSOR)
			-- Move cursor to position `p'.
		require -- from CURSOR_STRUCTURE
			cursor_position_valid: valid_cursor (p)

	has (v: EV_WIDGET): BOOLEAN
			-- Does `Current' contain `v'?
		require -- from  CONTAINER
			True
		ensure -- from CONTAINER
			not_found_in_empty: Result implies not is_empty

	index: INTEGER_32
			-- Current position.

	move (i: INTEGER_32)
			-- Move cursor `i' positions. The cursor
			-- may end up off if the absolute value of `i'
			-- is too big.
		ensure -- from CHAIN
			too_far_right: (old index + i > count) implies exhausted
			too_far_left: (old index + i < 1) implies exhausted
			expected_index: (not exhausted) implies (index = old index + i)

	valid_cursor (p: CURSOR): BOOLEAN
			-- Can the cursor be moved to position `p'?
			-- This is True if `p' conforms to EV_DYNAMIC_LIST_CURSOR and
			-- if it points to an item, `Current' must have it.

	wipe_out
			-- Remove all items.
		require -- from COLLECTION
			prunable: prunable
		ensure -- from COLLECTION
			wiped_out: is_empty
	
feature -- Measurement 

	height: INTEGER_32
			-- Vertical size in pixels.
			-- Same as minimum_height when not displayed.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.height

	minimum_height: INTEGER_32
			-- Lower bound on height in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.minimum_height
			positive_or_zero: Result >= 0

	minimum_width: INTEGER_32
			-- Lower bound on width in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.minimum_width
			positive_or_zero: Result >= 0

	width: INTEGER_32
			-- Horizontal size in pixels.
			-- Same as minimum_width when not displayed.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.width

	x_position: INTEGER_32
			-- Horizontal offset relative to parent x_position in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.x_position

	y_position: INTEGER_32
			-- Vertical offset relative to parent y_position in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.y_position
	
feature -- Output

	io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of tagged_out.
			-- (from ANY)

	print (some: ANY)
			-- Write terse external representation of `some'
			-- on standard output.
			-- (from ANY)

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of out.
			-- (from ANY)
	
feature -- Platform

	operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
	
feature -- Status Report

	is_destroyed: BOOLEAN
			-- Is `Current' no longer usable?
			-- (from EV_ANY)
		ensure -- from EV_ANY
			bridge_ok: Result = implementation.is_destroyed
	
feature -- Status settings

	disable_homogeneous
			-- Allow items to have varying sizes.
		require
			not_destroyed: not is_destroyed
		ensure
			is_not_homogeneous: not is_homogeneous

	enable_homogeneous
			-- Set each item in `Current' to be equal in size
			-- to that of the largest item.
		require
			not_destroyed: not is_destroyed
		ensure
			is_homogeneous: is_homogeneous

	resize (a_column, a_row: INTEGER_32)
			-- Resize the table to hold `a_column' by `a_row' widgets.
		require
			not_destroyed: not is_destroyed
			a_column_positive: a_column >= 1
			a_row_positive: a_row >= 1
			columns_resizeable: columns_resizable_to (a_column)
			rows_resizeable: rows_resizable_to (a_row)
		ensure
			columns_set: columns = a_column
			rows_set: rows = a_row
			items_untouched: linear_representation.is_equal (old linear_representation)

	set_border_width (a_value: INTEGER_32)
			-- Assign `a_value' to border_width.
		require
			not_destroyed: not is_destroyed
			positive_value: a_value >= 0
		ensure
			border_width_set: border_width = a_value

	set_column_spacing (a_value: INTEGER_32)
			-- Assign `a_value' to the spacing in-between columns, in pixels.
		require
			not_destroyed: not is_destroyed
			positive_value: a_value >= 0
		ensure
			column_spacing_set: column_spacing = a_value

	set_item_position (v: EV_WIDGET; a_column, a_row: INTEGER_32)
			-- Move `v' to position `a_column', `a_row'.
		require
			not_destroyed: not is_destroyed
			v_contained: has (v)
			a_column_positive: a_column >= 1
			a_row_positive: a_row >= 1
			table_wide_enough: a_column + (item_column_span (v) - 1) <= columns
			table_tall_enough: a_row + (item_row_span (v) - 1) <= rows
			table_area_clear: area_clear_excluding_widget (v, a_column, a_row, item_column_span (v), item_row_span (v))
		ensure
			position_set: item_column_position (v) = a_column and item_row_position (v) = a_row
			span_unchanged: item_column_span (v) = old item_column_span (v) and item_row_span (v) = old item_row_span (v)

	set_item_position_and_span (v: EV_WIDGET; a_column, a_row, column_span, row_span: INTEGER_32)
			-- Move `v' to `a_column', `a_row', and resize to occupy `column_span' columns and `row_span' rows.
		require
			not_destroyed: not is_destroyed
			v_not_void: v /= Void
			v_current: v /= Current
			v_contained: has (v)
			a_column_positive: a_column >= 1
			a_row_positive: a_row >= 1
			column_span_positive: column_span >= 1
			row_span_positive: row_span >= 1
			table_wide_enough: a_column + (column_span - 1) <= columns
			table_tall_enough: a_row + (row_span - 1) <= rows
			table_area_clear: area_clear_excluding_widget (v, a_column, a_row, column_span, row_span)
		ensure
			position_set: item_column_position (v) = a_column and item_row_position (v) = a_row
			span_set: item_column_span (v) = column_span and item_row_span (v) = row_span

	set_item_span (v: EV_WIDGET; column_span, row_span: INTEGER_32)
			-- Resize `v' to occupy `column_span' columns and `row_span' rows.
		require
			not_destroyed: not is_destroyed
			v_contained: has (v)
			column_span_positive: column_span >= 1
			row_span_positive: row_span >= 1
			table_wide_enough: item_column_position (v) + column_span - 1 <= columns
			table_tall_enough: item_row_position (v) + row_span - 1 <= rows
			table_area_clear: area_clear_excluding_widget (v, item_column_position (v), item_row_position (v), column_span, row_span)
		ensure
			span_set: item_column_span (v) = column_span and item_row_span (v) = row_span
			position_unchanged: item_column_position (v) = old item_column_position (v) and item_row_position (v) = old item_row_position (v)

	set_row_spacing (a_value: INTEGER_32)
			-- Assign `a_value' to the spacing in-between rows, in pixels.
		require
			not_destroyed: not is_destroyed
			positive_value: a_value >= 0
		ensure
			row_spacing_set: row_spacing = a_value
	
invariant
	columns_positive: columns >= 1
	rows_positive: rows >= 1

		-- from EV_CONTAINER
	client_width_within_bounds: is_usable implies client_width >= 0 and client_width <= width
	client_height_within_bounds: is_usable implies client_height >= 0 and client_height <= height
	all_radio_buttons_connected: is_usable implies all_radio_buttons_connected
	parent_of_items_is_current: is_usable implies parent_of_items_is_current
	items_unique: is_usable implies items_unique

		-- from EV_WIDGET
	pointer_position_not_void: is_usable and is_show_requested implies pointer_position /= Void
	is_displayed_implies_show_requested: is_usable and then is_displayed implies is_show_requested
	parent_contains_current: is_usable and then parent /= Void implies parent.has (Current)

		-- from EV_PICK_AND_DROPABLE
	user_interface_modes_mutually_exclusive: mode_is_pick_and_drop.to_integer + mode_is_drag_and_drop.to_integer + mode_is_target_menu.to_integer = 1

		-- from EV_ANY
	is_initialized: is_initialized
	is_coupled: implementation /= Void and then implementation.interface = Current
	default_create_called: default_create_called

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

		-- from EV_DOCKABLE_SOURCE
	parent_permits_docking: is_dockable implies parent_of_source_allows_docking

		-- from EV_COLORIZABLE
	background_color_not_void: is_usable implies background_color /= Void
	foreground_color_not_void: is_usable implies foreground_color /= Void

		-- from EV_POSITIONED
	width_not_negative: is_usable implies width >= 0
	height_not_negative: is_usable implies height >= 0
	minimum_width_not_negative: is_usable implies minimum_width >= 0
	minimum_height_not_negative: is_usable implies minimum_height >= 0

		-- from CHAIN
	non_negative_index: index >= 0
	index_small_enough: index <= count + 1
	off_definition: off = ((index = 0) or (index = count + 1))
	isfirst_definition: isfirst = ((not is_empty) and (index = 1))
	islast_definition: islast = ((not is_empty) and (index = count))
	item_corresponds_to_index: (not off) implies (item = i_th (index))
	index_set_has_same_count: index_set.count = count

		-- from ACTIVE
	writable_constraint: writable implies readable
	empty_constraint: is_empty implies (not readable) and (not writable)

		-- from INDEXABLE
	index_set_not_void: index_set /= Void

		-- from BILINEAR
	not_both: not (after and before)
	before_constraint: before implies off

		-- from LINEAR
	after_constraint: after implies off

		-- from TRAVERSABLE
	empty_constraint: is_empty implies off

		-- from FINITE
	empty_definition: is_empty = (count = 0)
	non_negative_count: count >= 0

indexing
	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
	source: "[
		Eiffel Software
		356 Storke Road, Goleta, CA 93117 USA
		Telephone 805-685-1006, Fax 805-685-6869
		Website http://www.eiffel.com
		Customer support http://support.eiffel.com
	]"

end -- class EV_TABLE