The stream automatically flushes after data size exceeds the
size we deem for INCR chunks, but we still try to copy it all.
Actually limit the data we copy, and leave the rest for future
INCR chunks.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1198
INCR transfers are mandated to finish with a final 0-size XChangeProperty
roundtrip after the final data chunk. Actually honor this and ensure we
iterate just once more for this.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1198
This seemed to work under the assumption that a flush() call can
only result in one INCR roundtrip. This is evidently not true, so
we should hold things off until all pending data is actually flushed.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1198
If say we want 32bit data, but have 2 bytes stored, we would simply
ignore flush requests. Allow (and don't clear) the needs_flush flag
if we have less than the element size accumulated.
Instead handle this in can_flush(), so it's triggered whenever we
have enough data to fill 1 element, or if the stream is closing
(seems a broken situation, but triggered by the caller).
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1198
XMaxRequestSize/XMaxExtendedRequestSize are documented to return
the maximum size in 4-byte units, whereas we are comparing this
to byte lenghts. We can afford 4x the data here.
Since I don't know the payload size of the XChangeProperty request,
be generous and allot 400 bytes for it, we have some to spare.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1198
Better to have the relevant object figure out whether it is a good
position to be unredirectable other than the actor, which should be
responsible for being composited.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/798
This removes the MetaWindowX11::priv pointer. It is replaced with a
meta_window_x11_get_private() helper function, and another method to get
the client rect without going through MetaWindowX11Private.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/798
Most visible with xwayland-on-demand, at the time of setting things up
for X11 selections, we don't forward the current state. This makes the
first started X11 app oblivious to eg. the current clipboard.
Syncing selections up at the time of initializing the X11 selection
stuff ensures that doesn't happen.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1186
This is so that cogl-trace.h can start using things from cogl-macros.h,
and so that it doesn't leak cogl-config.h into the world, while exposing
it to e.g. gnome-shell so that it can make use of it as well. There is
no practical reason why we shouldn't just include cogl-trace.h via
cogl.h as we do with everything else.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/1059
This error was just logged but not raised. Do as the code comment said
and raise a pipe error at that moment, and for subsequent operations
on the output stream (although none besides close() should be expected
after propagating the error properly).
Related: https://gitlab.gnome.org/GNOME/mutter/issues/1065
To keep consistent and avoid confusion, rename the function:
`meta_window_x11_buffer_rect_to_frame_rect()`
to:
`meta_window_x11_surface_rect_to_frame_rect()`
As this function doesn't deal with the `window->buffer_rect` at all.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/1091
This commits adds support on the MetaWindow and constraints engine side
for asynchronously repositioning a window with a placement rule, either
due to environmental changes (e.g. parent moved) or explicitly done so
via `meta_window_update_placement_rule()`.
This is so far unused, as placement rules where this functionality is
triggered are not yet constructed by the xdg-shell implementation, and
no users of `meta_window_update_placement_rule()` exists yet.
To summarize, it works by making it possible to produce placement rules
with the parent rectangle a window should be placed against, while
creating a pending configuration that is not applied until acknowledged
by the client using the xdg-shell configure/ack_configure mechanisms.
An "temporary" constrain result is added to deal with situations
where the client window *must* move immediately even though it has not yet
acknowledged a new configuration that was sent. This happens for example
when the parent window is moved, causing the popup window to change its
relative position e.g. because it ended up partially off-screen. In this
situation, the temporary position corresponds to the result of the
movement of the parent, while the pending (asynchronously configured)
position is the relative one given the new constraining result.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/705
MetaGravity is an enum, where the values match the X11 macros used for
gravity, with the exception that `ForgetGravity` was renamed
`META_GRAVITY_NONE` to have less of a obscure name.
The motivation for this is to rely less on libX11 data types and macros
in generic code.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/705
A placement rule placed window positions itself relative to its parent,
thus converting between relative coordinates to absolute coordinates,
then back to relative coordinates implies unwanted restrictions for
example when the absolute coordinate should not be calculated againts
the current parent window position.
Deal with this by keeping track of the relative position all the way
from the constraining engine to the move-resize window implementation.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/705
MetaX11SelectionOutputStream was storing copies of strings only to use
them in init and then free them in finalize. This was also causing a
small leak, because one of these strings was not freed. Instead of doing
that just don't create these unnecessary copies in the first place.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/1001
To address the black shadows that sometimes show during resize with
Xwayland, we need to update the window shape regardless of the frozen
status of the window actor.
However, plain Xorg does not need this, as resized windows do not clear
to black, so add a new vfunc to window/x11 to indicate whether or not
the backing windowing system (either plain X11 or Xwayland) would
require the shape to be always updated.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/942
Make sure we freeze commits before resizing the window as this will
clear the frame to black.
Set the "thaw on paint" flag so that the post paint for window actor X11
can then thaw the freeze initiated prior to the resize and keep the
freeze/thaw balanced.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/942
To be able to thaw commits following a resize that might have frozen
commits, to keep freezes and thaws even, we need a way to tell whether
a repaint should also thaw commits.
Add a flag to `MetaWindowX11` and the appropriate functions to set and
query it.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/942
Xwayland may post damages for an X11 window as soon as the frame
callback is triggered, while the X11 window manager/compositor has not
yet finished updating the windows.
If Xwayland becomes compliant enough to not permit updates after the
buffer has been committed (see [1]), then the partial redraw of the X11
window at the time it was posted will show on screen.
To avoid that issue, the X11 window manager can use the X11 property
`_XWAYLAND_ALLOW_COMMITS` to control when Xwayland should be allowed to
post the pending damages.
Add `freeze_commits()` and `thaw_commits()` methods to `MetaWindowX11`
which are a no-op on plain X11, but sets `_XWAYLAND_ALLOW_COMMITS` on
the toplevel X11 windows running on Xwayland.
[1] https://gitlab.freedesktop.org/xorg/xserver/merge_requests/316
See-also: https://gitlab.gnome.org/GNOME/mutter/merge_requests/855https://gitlab.gnome.org/GNOME/mutter/merge_requests/942
At the moment we only disarm the watchdog timer set up for SYNC counter
requests if we're in the middle of a resize operation.
It's possible that the resize operation finished prematurely by the user
letting go of the mouse before the client responded. If that happens, when the
client finally updates mutter will erroneously still have the watchdog timer
engaged from before until it times out, leading to resizes for the next second
or so to not get processed, and the client to get blacklisted from future sync
requests.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/942
While most of the code to compute a window's layer isn't explicitly
windowing backend specific, it is in practice: On wayland there are
no DESKTOP windows(*), docks(*) or groups.
Reflect that by introducing a calculate_layer() vfunc that computes
(and sets) a window's layer.
(*) they shall burn in hell, amen!
https://gitlab.gnome.org/GNOME/mutter/merge_requests/949
This is inspired by 98892391d7 where the usage of
`g_signal_handler_disconnect()` without resetting the corresponding
handler id later resulted in a bug. Using `g_clear_signal_handler()`
makes sure we avoid similar bugs and is almost always the better
alternative. We use it for new code, let's clean up the old code to
also use it.
A further benefit is that it can get called even if the passed id is
0, allowing us to remove a lot of now unnessecary checks, and the fact
that `g_clear_signal_handler()` checks for the right type size, forcing us
to clean up all places where we used `guint` instead of `gulong`.
No functional changes intended here and all changes should be trivial,
thus bundled in one big commit.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/940
Java applications might use override-redirect windows as parent windows for
top-level windows, although this is not following the standard [1].
In such case, the first non-override-redirect child window that is created
was marked as being on_all_workspaces since the call to
should_be_on_all_workspaces() returns TRUE for its parent, and this even
though the on_all_workspaces_requested bit is unset.
When a further child of this window was added, it was set as not having a
workspace and not being on_all_workspaces, since the call to
should_be_on_all_workspaces() for its parent would return FALSE (unless if
it is in a different monitor, and the multiple-monitors workspaces are
disabled).
Since per commit 09bab98b we don't recompute the workspace if the
on_all_workspaces bit is unset, we could end up in a case where a window can
be nor in all the workspaces or in a specific workspace.
So let's just ignore the transient_for bit for a window if that points to an
override-redirect, using the x11 root window instead.
Add a stacking test to verify this scenario (was failing before of this
commit).
Fixes https://gitlab.gnome.org/GNOME/mutter/issues/885https://gitlab.gnome.org/GNOME/mutter/merge_requests/895
[1] https://standards.freedesktop.org/wm-spec/wm-spec-latest.html#idm140200472512128
Once we set the transient_for, we look for parent MetaWindow, so instead
of overwriting this value for loops check, just use another function
and avoid to look for the xwindow again when setting the MetaWindow parent.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/895
We ask XLib the next request serial number before performing other actions
triggered by meta_x11_display_set_input_focus_internal() that doesn't use
the request serial anyways. So, just request it before updating the focus
window as that's the operation that needs it.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/909
When using DesktopIcons extension and clicking in an icon, gnome-shell
starts an infinite loop caused by the first focus change that may trigger
on X11 a focus in/out event that leads to stage activation/deactivation
which never ends.
This happens because as part of meta_x11_display_set_input_focus_xwindow()
to focus the X11 stage window, we unset the display focus, but this also
causes to request the X11 display to unset the focus since we convolute by
calling meta_x11_display_set_input_focus() with no window, that leads to
focusing the no_focus_window and then a focus-in / focus-out dance that the
shell amplifies in order to give back the focus to the stage.
In order to fix this, mimic what meta_display_set_input_focus() does, but
without updating the X11 display, and so without implicitly calling
meta_x11_display_set_input_focus(), stopping the said convolution and
properly focusing the requested xwindow.
Also ensure that we're not doing this when using an older timestamp, since
this check isn't performed anymore.
Fixes https://gitlab.gnome.org/GNOME/mutter/issues/896
Fixes https://gitlab.gnome.org/GNOME/mutter/issues/899https://gitlab.gnome.org/GNOME/mutter/merge_requests/909
This is a workaround for X11 games which use randr to change the resolution
in combination with NET_WM_STATE_FULLSCREEN when going fullscreen.
Newer versions of Xwayland support the randr part of this by supporting randr
resolution change emulation in combination with using WPviewport to scale the
app's window (at the emulated resolution) to fill the entire monitor.
Apps using randr in combination with NET_WM_STATE_FULLSCREEN expect the
fullscreen window to have the size of the emulated randr resolution since
when running on regular Xorg the resolution will actually be changed and
after that going fullscreen through NET_WM_STATE_FULLSCREEN will size
the window to be equal to the new resolution.
We need to emulate this behavior for these games to work correctly.
Xwayland's emulated resolution is a per X11 client setting and Xwayland
will set a special _XWAYLAND_RANDR_EMU_MONITOR_RECTS property on the
toplevel windows of a client (and only those of that client), which has
changed the (emulated) resolution through a randr call.
This commit checks for that property and if it is set adjusts the fullscreen
monitor rect for this window to match the emulated resolution.
Here is a step-by-step of such an app going fullscreen:
1. App changes monitor resolution with randr.
2. Xwayland sets the _XWAYLAND_RANDR_EMU_MONITOR_RECTS property on all the
apps current and future windows. This property contains the origin of the
monitor for which the emulated resolution is set and the emulated
resolution.
3. App sets _NET_WM_FULLSCREEN.
4. We check the property and adjust the app's fullscreen size to match
the emulated resolution.
5. Xwayland sees a Window at monitor origin fully covering the emulated
monitor resolution. Xwayland sets a viewport making the emulated
resolution sized window cover the full actual monitor resolution.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/739
In a similar vein to commit 8fd55fef85. This notably failed when setting
the focus on the stage (eg. to redirect key events to Clutter actors).
Deeper in MetaDisplay focus updating machinery, it would check
meta_stage_is_focused() which would still return FALSE at the time it's
called.
This would not typically have side effects, but our "App does not respond"
dialogs see the focus change under their feet, so they try to bring
themselves to focus again. This results in a feedback loop.
Changing the order results in later checks on the X11 POV of the focus
being correct, so focus is not mistakenly stolen from the close dialog,
and it actually succeeds in keeping the key focus.
Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/issues/1607https://gitlab.gnome.org/GNOME/mutter/merge_requests/876
It might be the case that handling an event induces the stream to
trigger completion, hence removing itself from the list. In that
case we would operate on the no longer valid list element to fetch
the next one.
Keep a pointer to the next element beforehand, so we can tiptoe
over streams that did remove themselves.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/869
The streams were only detached from MetaX11Display (and its event handling)
on completion. This is too much to expect, and those might be in some
circumstances replaced while operating.
Make those streams detach themselves on dispose(), so we don't trip into
freed memory later on when trying to dispatch unrelated X11 selection events.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/869
Instead of passing around an X11 Display pointer that is retrieved from
the default Gdk backend, then finding the MetaX11Display from said X11
Display, pass the MetaX11Display directly.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/854
The functionality core/core.c and core/core.h provides are helpers for
the window decorations. This was not possible to derive from the name
itself, thus rename it and put it in the right place.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/854
Instead of storing the result of meta_prop_get_latin1_string() into
a temporary string value, g_strdup-ing that temp value storing the
g_strdup result into window->sm_client_id and then g_free-ing the
temporary string, we can pass window->sm_client_id as the place where
meta_prop_get_latin1_string() stores its result, since the result
from meta_prop_get_latin1_string() is itself a g_strdup-ed string,
so there is no need to g_strdup it again.
Note this drops the check to only issue the
"Window %s sets SM_CLIENT_ID on itself ..." warning once. This check is
not necessary as update_sm_hints() is only called once at window
creation time and is never called again.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/786
Use g_strdup instead of malloc + strcpy, this also gets rid of a bunch
of error checking which is no longer necessary, also adjust the free
path accordingly.
Note that there was a malloc + XFree mismatch in the removed error-handling.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/786
latin1_string_from_results and utf8_string_from_results use g_strndup,
so the returned string should be freed with g_free, rather then with
free or XFree. This fixes all free-s of buffers returned by these 2
functions to properly use g_free.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/786
Use g_new0 instead of calloc for motif_hints_from_results and adjust
its callers to use g_free.
Note that in the process_request_frame_extents function this replaces
the wrong original mismatch of calloc + XFree with a matching g_malloc +
g_free pair.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/786
The meta_display_update_focus_window() call has indirect dependencies
on the X11 focus window, in order to determine the correct focus window
on the Wayland side (i.e. may turn out NULL with certain X windows).
In order to have the right x11_display->focus_xwindow there, we should
perform first the focus update on the X11 display.
Fixes focusing of Java applications, as those don't seem to go through
_NET_ACTIVE_WINDOW.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/819
Instead of open coding the X11 focus management in display.c, expose
it as a single function with similar arguments to its MetaDisplay
counterpart. This just means less X11 specifics in display.c.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/751
MetaDisplay and MetaX11Display focus windows are slightly decoupled,
we cannot rely here on the MetaDisplay focus to be updated yet. We
however know the X Window that got focused, so lookup the corresponding
MetaWindow (and client X window) from it.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/751
If window decoration is modified within a short period of time, mutter
sometimes starts processing the second request before the first
UnmapNotify event has been received. In this situation, it considers
that the window is not mapped and does not expect another UnmapNotify /
MapNotify event sequence to happen.
This adds a separate counter to keep track of the pending reparents. The
input focus is then restored when MapNotify event is received iff all
the expected pending ReparentNotify events have been received.
Signed-off-by: Rémi Bernon <rbernon@codeweavers.com>
https://gitlab.gnome.org/GNOME/mutter/merge_requests/657
If an application provides its window icon via wmhints, then mutter
loads the pixmap specified by the application into a cairo xlib surface. When
creating the surface it specifies the visual, indirectly, via an XRender
picture format.
This is suboptimal, since XRender picture formats don't have a way to specify
16bpp depth, which an application may be using.
In particular, applications are likely to use 16bpp depth pixmaps for their
icons, if the video card offers a 16bpp framebuffer/root window.
This commit drops the XRender middleman, and just tells cairo a visual to use
directly.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/715
We indirectly were relying on the MetaX11Stack for this. We strictly
need the _NET_CLIENT_LIST* property updates there, so move our own
internal synchronization to common code.
Fixes stacking changes of windows while there's no MetaX11Display.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/730
The end goal is to have all clutter backend code in src/backends. Input
is the larger chunk of it, which is now part of our specific
MutterClutterBackendX11, this extends to device manager, input devices,
tools and keymap.
This was supposed to be nice and incremental, but there's no sane way
to cut this through. As a result of the refactor, a number of private
Clutter functions are now exported for external backends to be possible.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/672
Introduce MetaCompositorX11, dealing with being a X11 compositor, and
MetaCompositorServer, being a compositor while also being the display
server itself, e.g. a Wayland display server.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/727
Unmanaging the windows may trigger stack operations that we later try
to synchronize despite being in dispose() stage. This may trigger
MetaStackTracker warnings when trying to apply those operations.
Switching destruction order (First dispose the X11 stack representation,
then unmanage windows) won't trigger further stack changes on X11 windows
after having signaled MetaDisplay::x11-display-closing.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/709
In the case mutter is a x11 compositor, it doesn't matter much
since the stack tracker will go away soon. In the case this is a
wayland compositor with mandatory Xwayland, it matters even less
since the session would be shutting down in those paths.
But if this a wayland compositor that can start Xwayland on demand,
this is even harmful, as the MetaStackTracker should be cleared of
x11 windows at this moment, and we actually did right before dispose
on ::x11-display-closing.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/709
The default configuration of libinput-gestures utility invokes wmctrl to
switch between desktops. It uses wmctrl because this works on both Xorg
and Wayland (via XWayland). Unfortunately, this generates the following
warning message every time, in both Xorg and Wayland desktops:
"Received a NET_CURRENT_DESKTOP message from a broken (outdated) client
who sent a 0 timestamp"
The desktop switch still works fine. The tiny code change here removes
this specific warning because, as the prefacing code comment originally
said and still says, older clients can validly pass a 0 time value so
why complain about that?
I also refactored the "if (workspace)" code slightly to avoid the double
test of the workspace value.
This is submitted for MR
https://gitlab.gnome.org/GNOME/mutter/merge_requests/671.
Starting with commit 2db94e2e we try to focus a fallback default focus window
if no take-focus window candidate gets the input focus when we request it and
we limit the focus candidates to the current window's workspace.
However, if the window is unmanaging, the workspace might be unset, and we could
end up in deferencing a NULL pointer causing a crash.
So, in case the window's workspace is unset, just use the currently active
workspace for the display.
Closes https://gitlab.gnome.org/GNOME/mutter/issues/687https://gitlab.gnome.org/GNOME/mutter/merge_requests/688
As per commit f71151a5 we focus an input window if no take-focus-window accepts
it. This might lead to an infinite loop if there are various focusable but
non-input windows in the stack.
When the current focus window is unmanaging and we're trying to focus a
WM_TAKE_FOCUS window, we intent to give the focus to the first focusable input
window in the stack.
However, if an application (such as the Java ones) only uses non-input
WM_TAKE_FOCUS windows, are not requesting these ones to get the focus. This
might lead to a state where no window is focused, or a wrong one is.
So, instead of only focus the first eventually input window available, try to
request to all the take-focus windows that are in the stack between the
destroyed one and the first input one to acquire the input focus.
Use a queue to keep track of those windows, that is passed around stealing
ownership, while we protect for unmanaged queued windows.
Also, reduce the default timeout value, as the previous one might lead to an
excessive long wait.
Added metatests verifying these situations.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/660https://gitlab.gnome.org/GNOME/mutter/merge_requests/669
As per commit f71151a5 we were ignoring WM_TAKE_FOCUS-only windows as focus
targets, however this might end-up in an infinite loop if there are multiple
non-input windows stacked.
So, accept any focusable window as fallback focus target even if it's a
take-focus one (that might not reply to the request).
Added a stacking test to verify this.
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/660https://gitlab.gnome.org/GNOME/mutter/merge_requests/669
When looking for the best fallback focus window, we ignore it if it is in the
unmanaging state, but meta_stack_get_default_focus_window() does this is check
for us already.
So, ignore the redundant test.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/669
We need to set XdndAware and XdndProxy on the stage window if running
a X11 compositor, this is not necessary on wayland.
Takes over gnome-shell code doing this initialization.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/667
When requesting to a take-focus window to acquire the input, the client may or
may not respond with a SetInputFocus (this doesn't happen for no-input gtk
windows in fact [to be fixed there too]), in such case we were unsetting the
focus while waiting the reply.
In case the client won't respond, we wait for a small delay (set to 250 ms) for
the take-focus window to grab the input focus before setting it to the default
window.
Added a test for this behavior and for the case in which a window takes the
focus meanwhile we're waiting to focus the default window.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/307
On FreeBSD, gethostname is guarded by '__POSIX_VISIBLE >= 200112', which
requires either '_POSIX_C_SOURCE >= 200112' or '_XOPEN_SOURCE >= 600'.
Defining _XOPEN_SOURCE to 500 does not break the build because of
implicit declaration, but it defeats the purpose of defining the macro.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/638
Starting from commit 7713006f5, during X11 disposition we also unmanage the
windows using the xids hash table values list.
However, this is also populated by the X11 Meta barrier implementation and then
contains both Windows and Barriers.
So when going through the values list, check whether we're handling a window or
a barrier and based on that, unmanage or destroy it.
Fixes https://gitlab.gnome.org/GNOME/mutter/issues/624https://gitlab.gnome.org/GNOME/mutter/merge_requests/605
Since commit 956ab4bd made libcanberra mandatory, we never use
the system bell for handling the `audible-bell` setting. So
instead of reacting to settings changes with the exact same call
to XkbChangeEnabledControls(), just call it once when initializing.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/598
In all places (including src/wayland) we tap into meta_x11_display* focus
API, which then calls meta_display* API. This relation is backwards, so
rework input focus management so it's the other way around.
We now have high-level meta_display_(un)set_input_focus functions, which
perform the backend-independent maintenance, and calls into the X11
functions where relevant. These functions are what callers should use.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/420
This object takes care of the X11 representation of the window stack,
namely the _NET_CLIENT_LIST and _NET_CLIENT_LIST_STACKING root window
properties.
This code has been lifted from src/core/stack.c into src/x11 as it's
dependent on the X11 display availability. This also leaves MetaStack
squeaky clean of x11 specifics.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/420
