Focus the internal fallback window when focus is transfered to a window that...

Focus the internal fallback window when focus is transfered to a window that doesn't have InputHint set but still use WM_PROTOCOLS_TAKE_FOCUS (ie, there is no way for the window manager to tell whether or not the client will accept focus in the end since focus is set by the client alone through the 'take focus' mechanism) - Fix bug #1853 without breaking #2410

(Old svn revision: 24169)