Some of the mutter code using these properties expects them to be
null-terminated whereas xcb does not use null-terminated strings:
http://xcb.freedesktop.org/XcbRationale/
This was in some cases resulting in the WM_CLASS property containing
garbage data which broke application matching, caused the hot-corner and
window-switcher to stop working, or was exposed as text in the UI.
https://bugzilla.gnome.org/show_bug.cgi?id=759658
Both Window and XSyncCounter are XIDs which on 64 bit X clients are 8
bytes wide. But the values on the wire are 32 bit so, for these types,
we always copy 4 bytes into results->prop. As such copying them out
with a cast such as *(Window *) means that we are actually reading 8
bytes which depending on whether the higher addressed 4 bytes are zero
means that sometimes this works while others it gives us a bogus
value.
https://bugzilla.gnome.org/show_bug.cgi?id=756074
It seems the largest possible value is to be passed, so actually pass
that instead. Note that even though the name of the xcb_get_property
parameter is called 'long_length' its actually a uint32_t.
https://bugzilla.gnome.org/show_bug.cgi?id=751136
It's been long enough. We can mandate support for these, at least
at build-time. The code doesn't actually compile without either
of these, so just consider that unsupported.
This is specifically about managing X11 windows, not necessarily
running as an X11 compositor. By that I mean that this code is
still used for XWayland windows, and event handling is still and
modesetting / monitor management is still in core/.
This is also a fairly conservative move. We don't move anything
like screen.c or bell.c in here, even though those are really
only for X11 clients.
