The measure tool displays the distance and bearing between two points in your image.
To measure, click and drag using Button1 between two points. Each point can be dragged to a new position.
Measure Tool Settings
The Use Info Window checkbox will toggle the sending of imformation to the Info Window Dialog .
The key combination: Ctrl-Button1 can be used to constrain the end points to a horizontal line. If needs require positioning without constraint, simply release Ctrl prior to releasing Button1.
The key combination: Alt-Button1 can be used to constrain the end points to a vertical line. If needs require positioning without constraint, simply release Alt prior to releasing Button1.