Blurry titlebar font when window is not maximized
Metacity window manager and Compiz window manager using gtk-window-decorator render slightly blurry titlebar fonts for windows that are not maximized. The fonts appear to lack sub-pixel hinting and/or anti-aliasing. Maximized windows render sharp fonts.
The clip_to_rounded_corners() function in libmetacity is called to draw rounded corners for the un-maximized windows in my theme. It seems the call to draw rounded corners by cairo_arc() in that function somehow affects the font rendering. When windows are maximized, the drawing of rounded corners is not performed, hence the sharp font rendering.
More info about this issue is reported at: https://bugs.launchpad.net/ubuntu/+source/metacity/+bug/1780468