If we attach to a MetaWindow that disappears before the idle fires,
we'll notice that we can't associate the window properly again and
try to access data on the MetaWindow struct, which might crash.
Install a weak ref that ties the lifetime of the idle to the lifetime
of the MetaWindow.
It seems every GTK+ app does this for some reason at startup. This
is really unfortunate, since we'll have to create and destroy a new
MetaWindow really quickly.
Scale surfaces based on output scale and the buffer scale set by them.
We pick the scale factor of the monitor there are mostly on.
We only handle native i.e non xwayland / legacy clients yet.
https://bugzilla.gnome.org/show_bug.cgi?id=728902
Advertise the scale factor on the output and transform pointer and damage
events as well as input and opaque regions for clients
that scale up by themselves i.e use set_buffer_scale.
We do not scale any 'legacy' apps yet.
https://bugzilla.gnome.org/show_bug.cgi?id=728902
Since commit 6e8d1d79d, move operations are always performed for
the (toplevel) parent of all transient, which is just plain silly
if the dialog is not actually attached to its parent (either because
the dialog is not modal or the setting is disabled).
We need the old rect for two purposes: to find the x/y in a resize-only
action, and to pass into the constraints code for nefarious purposes.
The constraints code takes a frame rectangle, so we convert the original
client rect into a frame rect, but never convert it back since it's
unused for the rest of the function.
Instead of playing games with the variables, just have two,
separately-scoped variables. One is the client rect, the other is the
frame rect.
Ugh. So in the fullscreen case, we need to make sure to specify that
it's a MOVE_ACTION so that we move to the saved position, but we
can't do that in the resizing case since we need to use the resized
rectangle.
The flags are really hurting us here. Perhaps we should make it the
client's responsibility to specify a complete rectangle which we
could resize to; then the weird-o logic would be self-contained in
each front-end.
I'm not convinced this covers all cases, especially when we could have
a dangling weird state pointer, but it fixes our existing two testcases.
For gravity-based resizing, we need to make sure that the requested
rectangle has the proper x/y position given by the gravity resize,
rather than the bogus root_x_nw / root_y_nw parameter.
Make the test for this more explicit.
Restoring the position in our move_resize_internal implementation
is too late. We need to do it at ack-time, before we hand off the
new position to the constraints code.
With our surface_mapped strategy, implement_showing might not
change whether the window has been shown or not, and thus we
might end up clearing pending_compositor_effect before the window
is mapped.
Only clear pending_compositor_effect when the effect has actually
been used.
For the server-initiated resize case, like unmaximize or some forms
of tiling, we dropped the x/y of the server-assigned rectangle on the
floor, which meant the surface didn't move to where it needed to be in
that case. Now, save it internally, and combine it with the dx/dy passed
in during attaches to figure out where we actually need to be.
Make sure to only use it for when we send out a configure notify. We
should use the passed in rectangle for other scenarios, like a
client-initiated resize.
This fixes incorrect surface placement after unmaximization.
For the server-initiated resize case, like unmaximize or some forms
of tiling, we dropped the x/y of the server-assigned rectangle on the
floor, which meant the surface didn't move to where it needed to be in
that case. Now, save it internally, and combine it with the dx/dy passed
in during attaches to figure out where we actually need to be.
This fixes incorrect surface placement after unmaximization.
Remove extend_by_frame and unextend_by_frame. Use a dumb hack in
window.c to translate into window geometry in back. We'll soon track
all rectangles in MetaWindow in terms of the window geometry.
Talking it over with Owen, we weren't sure why this was here.
At one point, we were creating a foreign stage window, so potentially
Clutter didn't select for its own events, but now we're using a standard
stage window, so this seems weird.
Why we did it on the COW, nobody knows. Maybe copy/paste bugginess?
Grab operations are now always taken on the backend connection, and
this breaks GTK+'s event handling.
Instead of taking a grab op, just do the handling ourselves. The
GTK+ connection will get an implicit grab, which means pointer /
keyboard events won't be sent to the rest of mutter, which is good.
When we click on a window with a passive grab, then the event_x
and event_y will be relative to that window, instead of relative to
the stage, which means that picking will be wrong.
Forcibly using root_x / root_y breaks nested mode. Nested mode is
a testing mode that should be replaced by a DRI3-enabled Xephyr,
though. It's getting too hairy to support properly.
Now that we grab devices on the X11 connection, we can run into
cross-connection issues. Since GTK+ frames are on the UI connection,
they'll get the passive grab when we click on them. Forcibly ungrab
on GTK+'s connection before attempting to take a grab on the backend
connection ourselves.
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.
Now that we have a global MetaScreen, we can simply have a global
MetaCursorTracker as well. Keep the get_for_screen() API around for
compatibility, though.
The Alt+F7 and Alt+F8 keybinds for moving and resizing windows allow you
to move and resize the window off the screen, so allow the same for the
menu items as well, since they're marked with the same accelerator.
https://bugzilla.gnome.org/show_bug.cgi?id=728617
This doesn't particularly matter, since we fall through into a default
case that does nothing right below, but this matches the other paths
and it prevents us from falling into a trap if we add other event types
below.
If we start a grab op from a keybind / menu, we'll handle the
ButtonPress and drop the grab then, never giving the window a chance
to handle what it needs to do before the grab is dropped.
This means that if you use Alt+F7 to move a window around, move it
to a side-tiling or maximization area, and then left-click, it will
just hang there in the sky.
The entire point of it was to check whether the window was on the
right screen. Since we don't handle multiple screens anymore, we
don't need to check anything anymore.
Looking at the code paths where is_mouse / is_keyboard are used,
all of them should never be run when dealing with a COMPOSITOR
grab op, since they're filtered out above or the method is just
never run during that time.
It's confusing that COMPOSITOR is in here, and requires us to
be funny with other places in code, so just take it out.
pointer->current needs to always be the surface under the pointer,
even when we have a grab. We do need to make sure we keep the focus
surface the same even when we have a grab, though, so add logic
for that.
In order to correctly fix the issue to make sure we only set the
focused surface to NULL during a grab, but not the current surface,
we need to merge update_current_surface back into repick_for_event
so we have more control over the behavior here.
... not when we do an update.
We only repick when we handle events, not when we update. Perhaps
this is a mistake.
Since update runs before handle_event, this means that when we
drop a grab, update will notice the NULL surface, since we haven't
repicked after the event, and then we'll repick the correct surface.
The end result is that you see a root cursor after a grab ends,
rather than the correct window cursor.
This doesn't fix it, since the current surface becomes NULL when
we start the grab. But it does make the code here more correct when
we fix that bug.
I was talking with other people and they became confused at the
term "double-buffered", since we were also talking about
double-buffering in general, e.g. swapping between two buffers.
Instead, we'll adapt the "pending state" nomenclature that we
already use for the field / variable names.
If we have a focused surface, we need to eat up key events, not
just if we have a non-empty focus resource list. The latter would
happen if we have a focused client but it never called get_keyboard.
The latest Xorg / Xwayland has support for -displayfd being used
in conjunction with an explicit display number. Use that to know
when the X server is ready, rather than UNIX signals, because
they're UNIX signals.
We track changes to windows fullscreen state and stacking order
to determine a monitor's in-fullscreen state, but missed the
obvious case of moving a fullscreen window between monitors.
https://bugzilla.gnome.org/show_bug.cgi?id=728395
Commit 585fdd781c not only removed the tabpopup, but set invalid
handlers (a.k.a. NULL) for those shortcuts; add back handling of
basic handling of those shortcuts by switching instantly without any
popups.
https://bugzilla.gnome.org/show_bug.cgi?id=728423
If we're sending out a configure event, we can't immediately move the
window; we need to instead wait to apply the new position when the
client sends a new buffer.
dx/dy should be against the regular window's rect, and need to
be ignored when we're resizing. Instead, we use gravity to anchor
the window's new rectangle when resizing.
Sophisticated clients, like those using ClutterGtk, will have more
than one focused resource per client, as both Clutter and GDK will
ask for a wl_pointer / wl_keyboard. Support this naturally using
the same "hack" as Weston: multiple resource lists, where we move
elements from one to the other.
In order to support multiple pointers for the same client, we're
going to need to kill it.
This will cause crashes for now, but will be fixed by the next
commit.
Doing this synchronously means that zenity tries to initialize GTK+.
Under Wayland, that will try to connect back to mutter as a display
server. We're waiting on zenity to exit, and zenity is waiting for
a connection response. Deadlock.
Simply assume that zenity will support all the options we feed it,
since it should be the correct version. Perhaps we should replace
our use of zenity with a simple helper binary that we know will
have all the right options if this still isn't good enough.
Our focus stealing prevention is still mostly inherited from metacity;
in particular, a (non-transient) window that is not on the current
workspace will not be given focus. This behavior made sense in the
GNOME 2 days, where workspaces were separated much more strictly.
However this is no longer the case in GNOME 3 - activating a launcher
will switch workspaces if necessary, and so will the app switcher.
There is no good reason to not do the same for other user actions
like clicking a URL or activating a search result, so allow activation
of windows on non-active workspaces if a proper timestamp is supplied,
assuming that this is a strong enough indication that we are dealing
with a legitimate user action.
https://bugzilla.gnome.org/show_bug.cgi?id=728018
Effectively we have been accepting CurrentTime timestamps for years,
but still complained about "stupid pagers" when encountering them;
just accept that we will never limit treating 0 timestamps as current
time to pagers.
https://bugzilla.gnome.org/show_bug.cgi?id=728018
The code that restacks X11 windows at the end first tracks any
old windows we know about, and then handles any windows created.
It starts when it ended, and then walks forwards and then
back looking for the first X11 window it doesn't know about.
However, when there aren't any X11 windows, it flies off the end
of the array and starts looking through random memory.
When it finds the X11 window, it then goes through and then tries
to restack the remaining windows according to how we've sorted
them.
Unfortunately, META_WINDOW_CLIENT_TYPE_X11 is 0, which is quite
common in random memory we have lying around, so we enter that
path and then just crash.
Fix the buffer overrun by adding the proper bounds check to the
search.
You can easily reproduce this by opening a menu while bloatpad
is full-screen. Why it only crashes when full-screen and not
when a standard window, I have no idea.
default_grab_focus tries to add implicit grab semantics where
focus won't take effect if there's a pointer button down. This
is not what we want for popup grabs at all, as it's perfectly
valid to want to drag on a menu while there's a button down.
The idea here is that while we take a WM-side grab, like a compositor
grab or a resizing grab, we need to remove the focus from the Wayland
client.
We make a special exception for CLICKING operations, because these
are really an internal state machine while you're pressing on a button
inside a frame, and in this case, we need to not kill the focus.
Really, it is a special case. When the subsurface is synchronous,
commit changes meaning from being applied immediately to being
queued up for replay later. Handle this explicit special case
with an explicit special case in the code.
This means that in all other paths, we can unconditionally
apply the actor immediately.
Even when it doesn't have a role.
This fixes cursors not quite working right, as they're a "detached"
surface without a role since nobody called set_cursor on them yet.
Instead of using commit_attached_buffer / actor_surface_commit.
We want to kill the return values of these methods because we
really should always be calling them, even if the surface doesn't
have a role.
This is also something that we did upstream. Since we want to
introduce an explicit "xdg_transient" window type for tooltips
and popovers, and since "transient_for" is a confusing dumb
80s term lifted from the ICCCM spec, just rename it.
This was changed upstream a little while ago for C++ compatibility.
It's also the more common term for the operation: you close a window,
you don't delete one. In fact, a delete event might seem like it
would be about resource management instead.
Except while reading _NET_WM_WINDOW_OPACITY, opacity is between 0 and 255. With
guint8, we'll get compiler warnings if arbitrary int values are passed.
https://bugzilla.gnome.org/show_bug.cgi?id=727874
This has one regression: the basic touch support added by
Carlos Garnacho in 991c85f is now partially reverted, since
we ported to Clutter events for this. We'll need to either
port his changes to Clutter, or restructure event handling
in mutter directly.
We can't really support the Gtk+ automatic scaling, as to much
code relies on the GdkWindow and XWindow sizes, etc to match.
In order to keep working we just disable the scaling, meaning
we will pick up the larger fonts, but nothing else. Its not
ideal but it works for now.
https://bugzilla.gnome.org/show_bug.cgi?id=706388
When _GTK_FRAME_EXTENTS changes, we need to redo constraints on
the window - this matters in particular if the toolkit removes
invisible borders when a window is maximized, since otherwise
the maximized window will be positioned as if it still has
invisible borders.
https://bugzilla.gnome.org/show_bug.cgi?id=714707
A gulong is not enough to get 64 bits in all arches, so we must
cast it, or we can corrupt the stack.
This was downstream bug bugzilla.redhat.com/show_bug.cgi?id=1002055
https://bugzilla.gnome.org/show_bug.cgi?id=707267
Apparently some connector technologies don't distinguish between
on and off, and there might be valid use cases for running without
any connected monitor.
In that case, just avoid any configuration at all.
https://bugzilla.gnome.org/show_bug.cgi?id=709009
Each level in the tower is initialized by binding the texture for that
level to an offscreen framebuffer and rendering the previous level as a
textured rectangle. The problem was that we were blending the previous
level with undefined data so argb32 windows with transparencies would
result in artefacts. This makes sure to disable blending when drawing
the textured rectangle.
After reading the atom, scale the value from 0xffffffff to 0xff. Not doing so
causes Clutter to truncate the opacity value, and only read the last two digits.
Hence, 0x7fffffff (50%) becomes 0xff (100%).
https://bugzilla.gnome.org/show_bug.cgi?id=727874
After reading the atom, scale the value from 0xffffffff to 0xff. Not doing so
causes Clutter to truncate the opacity value, and only read the last two digits.
Hence, 0x7fffffff (50%) becomes 0xff (100%).
https://bugzilla.gnome.org/show_bug.cgi?id=727874
A careful analysis of mutter's codebase shows that nothing actually
passes anything but 0 to this. gnome-shell has one instance, but it's
most likely a mistake.
Remove the grab_mask field and the one place in keybindings.c that uses it.
The parameter to begin_grab_op is left in for API compatibility reasons.
Since we get the ClientMessage after the surface is created, there's
no good way to synchronize the two streams. In this case, what we
need to do is delay the surface commit until after we get the
ClientMessage. Ideally, we'd be using a better surface system overall
where committing the surface didn't depend on what type it is, but
oh well, this is a good short-term hack for now.
This is effectively the same, but since we lose the xserver.xml protocol
in the new XWayland DDX, we have to use SIGUSR1 anyway, so might as well
switch over now.
The make_toplevel / window_unmanaging interface has never made
a lot of sense to me. Replace it with set_window, which does
effectively the same thing.
It's still not perfect in the case of XWayland, but I don't think
XWayland will ever make me happy.
It should be META_TYPE_WAYLAND_STAGE, not META_WAYLAND_TYPE_STAGE.
Well, actually, it *should* be META_TYPE_NATIVE_STAGE, because it's
not related to Wayland at all. But that comes later :)
Right now this just has all of the files in one directory. We'll
be introducing more structure to this in the future, and build
a proper backend system.
This will allow us to have a MetaCursorReference 'subclass' that's
lazily loaded. We currently always load all the images.
The long-term plan is to have a subclass for each "backend" and only
have CoglTexture as a common denominator. For the nested X11 backend,
we use XDefineCursor on our stage window. For the Wayland backend, we
would use set_cursor on our stage surface. For the native backend, we
would use the GBM code that's there right now.
The CoglTexture is there to be a "shared fallback" between all devices,
and also for the get_sprite API.
The odd man out is the X11 compositor case. For that, we need to move
the responsibility of setting the final cursor image out of
MetaCursorTracker, and simply have it be about tracking the used sprite
image and pointer position.
We want to make this private, and have MetaCursorReference be
backend-defined, with the texture possibly loaded on demand.
We can't make the definition of MetaCursorReference truly private yet
because of the XFixes cursor. A victim of MetaCursorTracker trying to
do too many things at once...
I want the MetaCursorTracker to mostly be about retrieving cursor
information. Start moving the code that loads cursor images to a
new file, MetaCursor. Eventually, MetaCursorTracker's APIs will
all take MetaCursorReferences, and we can have a clean backend
split here.
For whatever reason, this hash table was in the generic
implementation section instead of the XSync implementation,
even though it's only used by the XSync implementation.
Use it as a first pass of things to move over.
The reason we don't simply use gdk_window_add_filter directly is
because of some twisted idea that any GDK symbol being used from
core/ is a layer violation. While we certainly want to keep any
serious GDK code out of ui/, event handling is quite important
to have in core/, so simply use a GDK event filter directly.
The code here before was completely wrong. Not only did it mix up
coordinate spaces of "client rect" vs. "frame rect", but it used
meta_frame_get_frame_bounds, which is specifically for the *visible*
bounds of a window!
In the case that we don't have a bounding or input shape region at
all on the client window, the input shape that we should apply is
the surface's natural shape. So, set the region to NULL to get the
natural rect picking semantics.
Really, visible_to_compositor means that the window is shown, e.g.
not minimized. We need to be using a boolean tracking whether we've
called meta_compositor_add_window / meta_compositor_remove_window.
This fixes a jump during window placement when a window appears.
visible_to_compositor should always be in sync with show_window /
hide_window calls, even when unmananging.
This fixes a crash where we call sync_window_state when the window
is unmanaging, since we use visible_to_compositor to determine whether
the compositor will crash.
This is actually wrong; we should be using the knowledge about
whether we have called add_window / remove_window. We'll introduce
this with a new boolean next time.
We guarantee ourselves that a valid pixmap will appear any time
that the window is painted. The window actor will be scheduled
for a repaint if it's added / removed from the scene graph, like
during construction, if the size changes, or if we receive damage,
which are the existing use cases where this function is called.
So, I can't see any reason that we queue a redraw in here.
With the split into surface actors, we don't have an easy place
we can use to queue a redraw, and since it's unnecessary, we can
just drop it on the floor.
https://bugzilla.gnome.org/show_bug.cgi?id=720631
Compositors haven't been able to manage more than one screen for
quite a while. Merge MetaCompScreen into MetaCompositor, and update
the API to match.
We still keep MetaScreen in the public compositor API for compatibility
purposes.
We previously separated out MetaDisplay and MetaScreen. mutter
would only manage one screen, but we still kept a list of screens
for simplicity.
With Wayland support, we no longer care about the ability to
manage more than one screen at a time. Remove this by killing
the list of screens, in favor of having just one MetaScreen
in MetaDisplay.
We also kill off active_screen at the same time, since it's
not necessary anymore.
A future cleanup should merge MetaDisplay and MetaScreen. To avoid
breaking API, we should probably keep MetaScreen around as a dummy
type.
I'm a bit tired of hearing about this when I launch mutter-wayland
nested. Ideally, this would be part of display server integration,
not GNOME integration, so we could simply not make the call when
nested, but oh well.
cogl_texture_get_components can be used on both X11 and Wayland
backends. Technically, the detection is different: we actually
check the actual RENDER format in the old code, while Cogl simply
assumes that any pixmap with a depth >= 32 is ARGB32. Since Cogl
already seems to be working with its internal checks, it makes
more sense to use Cogl's check rather than keeping our own.
is_argb32 can be called at any time, including times when we don't
have a texture. In that case, just assume we're ARGB32. The value
really shouldn't be important though.
When I refactored this out into a vfunc, I forgot to change the
code that interprets the result flags to actually respect the
new FRAME_SHAPE_CHANGED result flag.
Since we weren't ever clearing the frame bounds, this meant that
the "shadow clip" wasn't ever updated as a result. Since right now
all Wayland surfaces are considered ARGB32, we always clip shadows
under frames, and thus shadows had this weird "punch-out" from the
first frame shape.
While the ICCCM mandates the use of this, it's not necessary under
a composited environment from my understanding, and it's a flat
out no-op under XWayland.
Looking at the other rootless servers like Xwin/Xquartz, it seems
that they contain code for colormap emulation, but they're actually
never used -- a bug prevents the code from ever being called. Given
that it's been this way since 2003, I'm going to hazard a guess that
not many apps using colormaps. Kill them off.
display.c is getting a bit crowded. Move most of the handling
out to another file, events.c.
The long-term goal is to have generic event handling here, with
backend-specific handling for the types of windows and such.
Previously, a sequence like this would crash a client:
=> surface.attach(buffer)
=> buffer.destroy()
The correct behavior is to wait until we release the buffer before
destroying it.
=> surface.attach(buffer)
=> surface.attach(buffer2)
<= buffer.release()
=> buffer.destroy()
The protocol upstream says that "the surface contents are undefined"
in a case like this. Personally, I think that this is broken behavior
and no client should ever do it, so I explicitly killed any client
that tried to do this.
But unfortunately, as we're all well aware, XWayland does this.
Rather than wait for XWayland to be fixed, let's just allow this.
Technically, since we always copy SHM buffers into GL textures, we
could release the buffer as soon as the Cogl texture is made.
Since we do this copy, the semantics we apply are that the texture is
"frozen" in time until another newer buffer is attached. For simple
clients that simply abort on exit and don't wait for the buffer event
anyhow, this has the added bonus that we'll get nice destroy animations.
If we have a CLICKING grab op we still need to send events to xwayland
so that we get them back for gtk+ to process thus we can't steer
wayland input focus away from it.
https://bugzilla.gnome.org/show_bug.cgi?id=726123
meta_wayland_seat_repick() can be called in various cases while mutter
has a GRAB_OP ongoing which means we could be sending wrong pointer
enter/leave events.
https://bugzilla.gnome.org/show_bug.cgi?id=726123
This ensures that we send the proper leave and enter events to wayland
clients.
Particularly, this solves a bug in SSD xwayland windows where clicking
and dragging on the title bar to move the window only works on the odd
turn (unless the pointer moves away from the title bar between
tries). This happens because xwayland gets a button press but doesn't
see the release so when it gets the next button press it discards it
because its pointer button tracking logic says that the button is
already pressed. Sending the proper wayland pointer leave event fixes
it since wayland clients must forget about button state at that point.
https://bugzilla.gnome.org/show_bug.cgi?id=726123
At one point, it was supported to run mutter without a compositor,
but we don't allow that any longer. A lot of code already assumes
display->compositor exists and doesn't check for a NULL pointer,
so just kill the rest of the checks.
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.
This is fairly simple and basic for now, with just skip_taskbar /
skip_pager, but eventually a lot of "WM policy" like this, including
move-resize, will be in subclasses for each individual surface.
In particular we need to know about all key events to keep the xkb
state reliable even if the event is then consumed by a global shortcut
or grab and never reaches any wayland client.
We also need to keep track of all pressed keys at all times so that we
can send an updated set or pressed keys to the focused client when a
grab ends.
https://bugzilla.gnome.org/show_bug.cgi?id=722847
Any given clutter event carries the modifier state as it was before it
occured but, for the wayland modifiers event, we want the state
including the current event.
To fix this, we'll keep our xkb_state instance around instead of the
serialized mods.
https://bugzilla.gnome.org/show_bug.cgi?id=722847
Currently touch events are ignored in the core event handler,
and hence dealt with within GDK. If those touch events were
emulating pointer events, GDK would attempt to convert back
those events to pointer events as the frame GdkWindow doesn't
have the GDK_TOUCH_MASK set.
This results in XI_TouchBegin events being initially processed
by GDK, converted to button events, and triggering a grab op
that subverts touch events into pointer events, so the touch
is never ever seen again by GDK. This leaves GDK in an
inconsistent internal state wrt pointer grabs, so future
pointer-emulating touches will refer to the same window forever.
Fix this by handling touch events minimally, just enough to
convert XI_TouchBegin to GDK_BUTTON_PRESS within mutter, so GDK
is bypassed for every touch event just like it is for pointer
events. This, and the XIGrabDevice() that keeps coercing pointer
events when the grab operation starts, are enough to fix window
drag and drop on touch devices.
https://bugzilla.gnome.org/show_bug.cgi?id=723552
We try to exempt CSD windows from being forced fullscreen if they are
undecorated and the size of the screen; however, we also catch almost
all windows that *do* need to be forced fullscreen in this check, since
they also have decorations turned off.
Identify actual CSD windows by checking whether _GTK_FRAME_EXTENTS is set -
GTK+ will always set this on CSD windows even if they have no invisible
borders or shadows at the current time.
We explicitly turn off the legacy-fullscreen check for native wayland windows
so we don't start legacy-fullscreening them if the new
meta_window_is_client_decorated() is later made more accurate.
https://bugzilla.gnome.org/show_bug.cgi?id=723029
We try to exempt CSD windows from being forced fullscreen if they are
undecorated and the size of the screen; however, we also catch almost
all windows that *do* need to be forced fullscreen in this check, since
they also have decorations turned off.
Identify actual CSD windows by checking whether _GTK_FRAME_EXTENTS is set -
GTK+ will always set this on CSD windows even if they have no invisible
borders or shadows at the current time.
https://bugzilla.gnome.org/show_bug.cgi?id=723029
