font operations are now done directly using Xlib calls, and the only
interaction with GDK within the x11font mechanism is to get the X ids
for drawables, GCs and the X display itself.
This should remove an obstacle to porting to GTK3, and also makes the
XFontStruct for loaded fonts more readily available, which I hope will
come in handy for another plan I have in mind.
[originally from svn r9289]