SUGGESTION: Shift - drag to draw straight lines

[RetroFuturistic]

Or any other modifier key to allow drawing a straight line.
The SHIFT key would be my preference, however, since it has become a quasi-standard for keeping drawing tools restrained (perfect squares instead of rectangles, circles instead of ovals, horizontal/vertical instead of wobbly lines)

This would turn the paintbrush into a great highlighter-pen. 

Was this ever implemented, perhaps instead of using SHIFT? Currently I have to save the screenshot in Screenshot Captor then open it in an external drawing program.

[tomos]

AFAIK this has not been implemented in Screenshot Captor.
Here a possible workaround:
I used use Skrommel's DragLock to constrain mouse movement adlong one axis. Was a long time ago but might still work
http://www.dcmembers.com/skrommel/download/draglock/
Related thread:
http://www.donationcoder.com/forum/index.php?topic=14009.0

[mouser]

If we're talking about the arrow drawing, try holding down Ctrl key. 

[RetroFuturistic]

@mouser -- control key does it -- thank you! I couldn't find where this was explained in the Help section or by searching the forum.

@tomos -- thanks for the tip about Skrommel's DragLock -- I'll keep it in mind. I see it was inspired by a suggestion from you and enjoyed reading the discussion post you linked to.