Windows now learn when the mouse cursor leaves or enters them.
Use this to implement GWidget::{enter,leave}_event() and use that
to implement the CoolBar button effect. :^)
I want to try an MS Office 97 "CoolBar" inspired look for my toolbars.
This is only the painting support, we still need hover events to implement
the actual effect.
Let GButton have an optional icon (GraphicsBitmap) that gets rendered in the
middle of the button if present.
Also add GraphicsBitmap::load_from_file() which allows mmap'ed RGBA32 files.
I wrote a little program to take "raw" files from GIMP and swizzle them into
the correct byte order.
