To emulate X11 grabs, mutter as a Wayland compositor would disable its
own keyboard shortcuts and when the X11 window is an override redirect
window (which never receives focus), it also forces keyboard focus onto
that X11 O-R window so that all keyboard events are routed to the
window, just like an X11 server would.
But that's a bit of a “all-or-nothing” approach which prevents
applications that would legitimately grab the keyboard under X11 (like
virtual machine viewers) to work by default.
Change “xwayland-allow-grabs” to control whether the keyboard focus
should be locked onto override redirect windows in case of an X11 grab.
For stringent needs, careful users can still use the blacklisting
feature (i.e. a list containing “!*”) to prevent grabs from any X11
applications to affect other Wayland native applications.
https://gitlab.gnome.org/GNOME/mutter/issues/597
If the surface is gone before `meta_xwayland_keyboard_grab_end()` is
called, we would bail out early leaving an empty grab, which will cause
a segfault as soon as a key is pressed later on.
Make sure we clean up the keyboard grab even if the surface is gone.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/255
This protocol is limited to Xwayland only and is not visible/usable by
any other client.
Mutter uses the following mechanisms to determine if an X11 client
should be granted a grab:
- is "xwayland-allow-grabs" set?
- if set, is the client blacklisted?
- otherwise, has the client set the X11 window property
_XWAYLAND_MAY_GRAB_KEYBOARD on the window using a client message?
- if not, is it a client white-listed either via the default system
list or the settings "xwayland-grab-access-rules"?
https://bugzilla.gnome.org/show_bug.cgi?id=783342
