I've been reading about Qt;
and I can see the most difficult aspect would be
custom placement of the icons
and having the program remember.
My latest idea is to have a "tooltabs" folder with txt files that define the tooltabs.
We would include a tooltab file for each category (lines, circles, modify, ...);
and users would have the option of creating custom tooltab files,
which would have exactly one action on each line:
Construction
DrawLine
DrawCircle
ModifyMirror
...
The order of the actions determines the order of the tooltab's icons,
and the first line (or maybe the file name) is the tooltab's title.
This seems like it would require a lot less coding;
all tooltabs could be created in a single loop.
And it also allows people to easily share / backup their tooltabs.
Users could look at the default tooltab files for insight,
and I could make a wiki article that briefly describes each action.
I might fork around with it...