Why can't we draw in the thumbnail Overview Workspace?

Just like we can in the Horizontal and Vertical Workspace.

Thumbnails exist as references to facilitate different forms of organization.

It might be useful being able to draw in them however the overhead involved would likely take an exponential toll on performance.

I seem to remember being able to it in an earlier version, maybe SBP 2. I think its something that is needed; better for designing a sequence rather than rendering it.

I neglected to mention I do not have SB and try to help by using Google. The ability was not stated in the guide where I could see it. However once you mentioned it may have been possible I started searching using different words that lead me to the information.

Apparently you can draw on the Panels in all versions of Storyboard. If you have tried but have not been able to it could be because you have “Forbid Drawing on Panel Thumbnails” checked in Preferences => General => General

http://docs.toonboom.com/help/storyboard-pro-5/storyboard/preferences/general-tab-preferences.html