[gtk+osx] patch 878461 updated again

[David B. <va...@nt...>]

This is mostly an improvement of gdkwindow rendering
after a gdkwindow has been unmapped them mapped again.

In GIMP terms, the tool window and preferences window
rendering has been improved when moving back and forth
between different tools or preferences.

The biggest remaining problem is now the lists.
Can anyone spot where the 'empty' bits of gtklist are
redraw after being unmapped, I can only see where
it redraws the items.

Dave