GTK+ Client Side Decorations: Fail
GTK+ developers have decided that window management belongs to the application. Specifically, it belongs to GNOME applications that now paint their decorations themselves. Unfortunately (but completely predictable) this creates problems for non-GNOME window managers under which applications now show double title bars.
Other problems with client side decorations look worse: Applications responsible for their own title bars cannot be closed (or even moved) when hung and can no longer have custom buttons for window actions like “put this window on all workspaces”.