LFCS 2012: X and Wayland

However, you can set the default decorations to empty rectangles and have your compositor to draw whatever decorations it wants to do. Some applications might ignore the setting and do whatever they want, but that's how they behave right now anyway.

Additionally, you can do tricks like overlaying a gray rectangle over an unresponsive application and drawing large "KILL" button on it to immediately kill the hung application.