Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
This patch adds a simple GMessageBox that can run in a nested event loop.
Here's how you use it:
GMessageBox box("Message text here", "Message window title");
int result = box.exec();
The next step is to make the WindowServer respect the modality flag of
these windows and prevent interaction with other windows in the same
process until the modal window has been closed.
