5fd0f62a62
A window can be unmanaged without asking the client to do it, for example as a side effect of a parent window being unmanaged, if the child window was a attached dialog. This means that the client might still make requests post updates to it after that it was unmapped. Handle this gracefully by NULL-checking the surface's MetaWindow pointer. We're not loosing any state due to this, as if the client wants to map the same surface again, it needs to either reassign it the toplevel role, or reset the xdg-toplevel, both resulting in all state being lost anyway. https://gitlab.gnome.org/GNOME/mutter/issues/240
Mutter
Mutter is a Wayland display server and X11 window manager and compositor library.
When used as a Wayland display server, it runs on top of KMS and libinput. It implements the compositor side of the Wayland core protocol as well as various protocol extensions. It also has functionality related to running X11 applications using Xwayland.
When used on top of Xorg it acts as a X11 window manager and compositing manager.
It contains functionality related to, among other things, window management, window compositing, focus tracking, workspace management, keybindings and monitor configuration.
Internally it uses a fork of Cogl, a hardware acceleration abstraction library used to simplify usage of OpenGL pipelines, as well as a fork af Clutter, a scene graph and user interface toolkit.
Mutter is used by GNOME Shell, the GNOME core user interface. It can also be run standalone, using the command "mutter", but just running plain mutter is only intended for debugging purposes.
License
Mutter is distributed under the terms of the GNU General Public License, version 2 or later. See the COPYING file for detalis.