[PATCH] ui/frames: check that compositing is not only requested, but also available.
Enabling code that is supposed to be used in compositing conditions is harmful if compositing is not actually available. Just checking the preference is not enough to make sure that compositing is available - the X server might be missing crucial extensions for compositing to work, which in turn correctly disables the internal compositor.
The end result is graphical issues like black borders around windows in such situations.
Make sure that compositing is both requested AND available to fix this bug.
Use Y2K38-unsafe startup-notification API sn_startup_sequence_get_last_active_time has a long where time_t should have been the right choice. This patch should be dropped as soon as Debian pkg startup-notification has moved on to contain an upstream fix.
