Adding widget to our rectangles

First you need a widget library.  Then we chain redraw call backs for any widget in the rectangle.

The libraries we have will work, they put widgets on windows by x and y.  The tracker will have call backs associated with rectangles of any size.  We can put all the tracked rectangles on the symbol table sorted by y x.  Find a widget window in six steps. Part of trackers job. But tracker needs to escape from io watch, and that means libev first..