Long time ago, I saw someone use a software (on Windows) that was specifically created to annotate pictures. It made it simple to add arrows, boxes, circles in "outstanding" colors to the image. Unfortunatly, I don't remember what program that was.
Now, I have to document a GUI and I'd like to use this software in order to annotate screenshots of the software so that I can show the order of flow and dependencies between various aspects of the GUI.
I'd be very happy if someone could point me into the right direction.