This has been disabled since February 2008, on the grounds that XFixes
didn't work reliably for hiding cursors. This has almost certainly been
fixed then and seems to work entirely reliably across a number of X
servers released in the past few years, and is definitely better than a
1x1 black dot for a cursor.
Helpfully though, where the spec states that the cursor will be hidden
when inside the specified window or one of its children, it actually
only uses the window to look up the Screen, and hides the cursor across
the entire Screen. So, when using this, we also need to track crossing
events.
If it's still broken, this needs to be fixed in the X server.
https://bugzilla.gnome.org/show_bug.cgi?id=690497
Signed-off-by: Daniel Stone <daniel@fooishbar.org>
1a0e501efd