Fixes bug 763023: in certain circumstances, XRRGetOutputInfo will return
a null pointer. This commit adds a check to detect and handle this
return value.
Otherwise WM-dependent default cursor is used, which does not
match our theme. Worse, later GDK will realize that we have
our own left_ptr cursor and will apply it after all, making
the discrepancy even more noticeable.
https://bugzilla.gnome.org/show_bug.cgi?id=762902
* Explicitly grab the device, setting appropriate cursor on it.
* Fix gdk_device_virtual_set_window_cursor() to just set the
cursor, without trying to check that mouse is over the given
window. Also prevent it from immediately resetting cursor.
* Alse take into account things that happen in other parts of
GDK - don't look for replacement cursor, GDK already did that,
and don't create a default arrow cursor instead of NULL,
GDK-W32 already did that up the stack as well.
Warn about inappropriate cursor == NULL argument instead.
https://bugzilla.gnome.org/show_bug.cgi?id=762711
Toplevels are now true layered windows that are moved,
resized and repainted via UpdateLayeredWindow() API call.
This achieves transparency without any extra effort,
and prevents window size and window contents desychronization
(bug 761629).
This also changes the way CSD windows are detected. We now
use window decorations to detect CSDiness of a window,
and to decide whether a window should be layered (CSD windows should
be) or not.
Decorations are now stored in the window implementation,
not as a quark-based property of the window-as-gobject.
https://bugzilla.gnome.org/show_bug.cgi?id=748872
Normally works only on CSD windows, non-CSD windows continue
to use WM modal loop for drag-resizing and drag-moving. However,
if it is activated on non-CSD windows, it does work.
Has the advantage of being completely immune to AeroSnap.
AeroSnap only worked partially on CSD windows, with the only part
that worked being "don't let users drag window titlebar outside of
the desktop". Now AeroSnap doesn't work on windows moved by
this code at all, which is good, since they currently don't work
well with it due to the way shadows are drawn.
It's possible to also re-implement AeroSnap (or something similar),
but that is a story for another commit.
This code was originally intended to fix the problem of window
size and window contents desynchronization, but failed to achieve
that result in the end. Nevertheless, it serves as a foundation for
other changes to the way window resizing works.
https://bugzilla.gnome.org/show_bug.cgi?id=761629
key repeat is handled client side, which means stalls in the compositor
dispatching key release events can lead to fictious repeat events.
This commit ties key repeat to a server roundtrip to ensure the client
and server are in sync.
https://bugzilla.gnome.org/show_bug.cgi?id=757942
We don't need the key repeat rate or anything like that when
handling key up events, so do key up events first before querying
for that information.
https://bugzilla.gnome.org/show_bug.cgi?id=757942
deliver_key_event is sometimes called from a timeout handler and
sometimes called directly. We currently erroneously return TRUE
(G_SOURCE_CONTINUE) in the case where it's called directly, but to
no ill effect, since we ignore that return value. In the future,
we're going to need to call it directly in other parts of the code
where the return value would be relevant and handling TRUE, would
require adding redundant code.
Instead, this commit just changes the code to always reset the timer
manually, and never rely on glib's ability to automatically reset
the timer by returning TRUE. This makes the code smaller, too, since
there's less special casing required.
https://bugzilla.gnome.org/show_bug.cgi?id=757942
If the parent of a transient is not a native Wayland window (e.g.
offscreen window), the transient loop check will crash.
Check for the actual type in the transient loop check and do not assume
the parent is necessarily Wayland native.
bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=761156
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
If there are already a window state event for a given window queued
when the window state is changed, drop that event and queue a new event
with a changed_mask based on the state before last event that was queue
without compression.
https://bugzilla.gnome.org/show_bug.cgi?id=762468
According to xdg_shell, an xdg_surface.configure with size 0x0 should
be interpreted as that it is up to the client to set a size.
When transitioning from maximize or fullscreen state, this means the
client should configure its size back to what it was before being
maximize or fullscreen.
This problem currently only occurs on weston because weston sends a
configure with size 0x0 when transitioning back from maximize or
fullscreen.
bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=762713
gdk_display_list_devices is deprecated and all the backends
implement the same fallback by delegating to the device manager
and caching the list (caching it is needed since the method does
not transfer ownership of the container).
The compat code can be shared among all backends and we can
initialize the list lazily only in the case someone calls the
deprecated method.
https://bugzilla.gnome.org/show_bug.cgi?id=762891
The staging buffer gets allocated any time begin_paint is called
on the window. This can happen even with an empty paint region,
so we should cope with that situation. At the moment we crash
trying to post a runtime warning.
https://bugzilla.gnome.org/show_bug.cgi?id=762755
The g_print documentation explicitly says not to do this, since
g_print is meant to be redirected by applications. Instead use
g_message for logging that can be triggered via GTK_DEBUG.
The g_print documentation explicitly says not to do this, since
g_print is meant to be redirected by applications. Instead use
g_message for logging that can be triggered via GTK_DEBUG.
The g_print documentation explicitly says not to do this, since
g_print is meant to be redirected by applications. Instead use
g_message for logging that can be triggered via GTK_DEBUG.
The g_print documentation explicitly says not to do this, since
g_print is meant to be redirected by applications. Instead use
g_message for logging that can be triggered via GTK_DEBUG.
gdk_display_add_seat was prepending new seats to the list, which
was effectively making the added seat the new default. Since that
is probably not intended, append to the list.
The gdkprivate-wayland.h header file is included from the top-level gdk
directory; this means that all included files referenced in the header
must be relative to the `gdk` directory, otherwise the build will fail
when the build directory is not equal to the source directory.
This commit fixes a build failure under continuous:
In file included from ../../gdk/gdkdisplaymanager.c:60:0:
../../gdk/wayland/gdkprivate-wayland.h:40:51: fatal error:
gtk-primary-selection-client-protocol.h: No such file or directory
#include "gtk-primary-selection-client-protocol.h"
^
compilation terminated.
Makefile:1155: recipe for target 'libgdk_3_la-gdkdisplaymanager.lo' failed
make[4]: *** [libgdk_3_la-gdkdisplaymanager.lo] Error 1
Except for the init function, all the visual related code is made
of gdkscreen vfuncs, so let's move it to gdkscreen-win32. This way
we avoid keeping other static variables and instead store the info
inside the screen struct.
I am testing GTK+ master against mutter 3.19.90, so I'd
like GTK+ to survive even when the compositor does not
support the primary selection interface.
Implement it using the internal copy of the protocol. Otherwise,
we just deal with it the same than clipboard selection, just mapping
it to the PRIMARY atom instead of the CLIPBOARD one.
https://bugzilla.gnome.org/show_bug.cgi?id=762561
This protocol is an internal mirror of the primary selection drafts
being proposed for wayland-protocols. No changes besides prefix/suffix
changes.
https://bugzilla.gnome.org/show_bug.cgi?id=762561
1f74f12d9 rendered entry of keypad decimal mark unuseable for
several national keyboard layouts, this commit amends that, at
least for W32, and makes GTK+ behave more or less the same way
W32 behaves.
The patch works like this:
- When typing the first character at the keyboard or when switching
keyboard layouts, the decimal mark character will be cached in the
static variable "decimal_mark" within gdkkeys-win32.c
- in case of WIN32, gdk_keyval_to_unicode() asks gdkkeys-win32.c for the
current decimal_mark when converting GDK_KEY_KP_Decimal.
https://bugzilla.gnome.org/show_bug.cgi?id=756751
1) MSDN says that the coordinates of the maximized window
must be specified as if the window was on the primary display,
even if nearest display where it ends up is not the primary display.
So instead of using nearest display work area verbatim,
use it only to account for taskbar size, while using
primary display top-left corner (0:0) as the reference point.
2) MSDN says that max tracking size is a system property, we
should just call GetSystemMetrics() and use that.
https://bugzilla.gnome.org/show_bug.cgi?id=762629
Sigh.
Now that we've neutered the QEMU USB tablet, I'm finding that
spice is doing just the same nonsense. It has a fake "spice vdagent
tablet". Blacklist that as well.
Remember the last source device we're generating multiple clicks for,
just so we can bail out if the device changed. That will just reset
the counting.
https://bugzilla.gnome.org/show_bug.cgi?id=723659
The significant change here is a memory leak fix in init_xrandr15.
The rest of the changes makes init_xrandr13 and init_xrandr15 more
parallel, and simplifies init_multihead.
Add a gtk_shell.set_startup_id request, so the application can communicate
to the compositor the startup id that it received through the
DESKTOP_STARTUP_ID envvar, or other means.
When running with a Wayland compositor which doesn't support the
xdg_shell interface, gtk+ will segfault while trying to access the
corresponding wl proxy.
Check for xdg_shell support and do not use Wayland if not present, so
that it can fallback to X11, hoping that Xwayland is usable.
Bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=762258
There is no point in attaching and then committing the same buffer if
there was no damage. This will also make us do less unnecessary backfill
read backs, for the cases where we paint with an empty paint region.
https://bugzilla.gnome.org/show_bug.cgi?id=762120
If a after-paint was scheduled but nothing was painted, for example when
the it was scheduled by a subsurface wanting to update its position,
we'd still try to read back from the backfill cairo surface and update
the committed cairo surface reference even though no buffer was
attached.
Fix this by adding a new state, 'pending_buffer_attached', which is only
true if a buffer was attached during frame. Only when this is true will
the backfill be read back and the committed cairo surface reference be
updated.
https://bugzilla.gnome.org/show_bug.cgi?id=762120
That way we can let ::cancel callers to override the visual
result of the operation (eg. when detaching notebook tabs on
NO_TARGET).
Also, document gdk_drag_drop_done() so it is mentioned that
this is a one-shot call.
https://bugzilla.gnome.org/show_bug.cgi?id=761954
We should conform to a minimal set of reasons for the gtk side to emit
a better GtkDragResult than GTK_DRAG_RESULT_ERROR. This fixes the notebook
tab DnD feature, where we rely on GTK_DRAG_RESULT_NO_TARGET.
In the wayland side, unfortunately we can't honor either NO_TARGET nor
USER_CANCELLED, we don't know of the latter, so we could return false
positives on the former.
https://bugzilla.gnome.org/show_bug.cgi?id=761954
The first time a window is shown we should always call SW_SHOWNORMAL.
Understand whether to call SW_SHOW or SW_SHOWNORMAL and the specific
ones for the temporary windows depending on IsWindowVisible.
This also fixes the problem when calling gtk_window_present and
the window is snapped to the left or right of the screen.
This patch is based on the patches provided by Yevgen Muntyan
and Aleksander Morgado.
https://bugzilla.gnome.org/show_bug.cgi?id=698652
If the window is iconified we want to restore the window
to get the proper size instead of showing it normal which
would change the size of the window.
https://bugzilla.gnome.org/show_bug.cgi?id=698652
Right now we use one buffer for both staged changes (freshly painted
changes waiting for the frame clock to send to the compositor) and
committed changes (changes actively being read by the compositor
process). This creates a problem in the event we need to stage updates
at the same time the compositor is processing committed updates: we
can't change what the compositor is actively processing.
The current solution for handling this contention is to allocate a
temporary buffer on the spot at the time the updates are staged, and to
copy that buffer back to the shared buffer later. The problem, though,
is that the copy to the shared buffer currently happens as soon as
the updates are finished being staged, not when the shared buffer is
done being processed by the compositor.
In order to address that problem, this commit changes the code to always
stage changes to a dedicated staging buffer. The staging buffer is
used exclusively by the client until the client is done with it, and then
once that staging buffer is committed, the client never writes to that
buffer again. If the client needs to stage new updates, it allocates a
brand new staging buffer, draws to it, and back fills the undrawn parts
of the buffer from a copy of the contents of the committed buffer.
As an optimization, the compositor has the option of releasing the
committed buffer back to the client. If it does so before the client
needs to stage new updates, then the client will reuse the buffer
for staging future updates. This optimization prevents having to allocate
a new staging buffer and the associated cost of back filling
that new buffer with a readback of the committed buffer.
https://bugzilla.gnome.org/show_bug.cgi?id=761312
Right now we handle buffer releases coming from the
compositor in a central place. We add a listener when
first creating the shared buffers.
This is problematic because a buffer can only have
one listener on it at once so users of the buffer
can't get notified when it's released.
This commit moves the buffer listener code from the
centrally managed display code to the cursor and window
code.
https://bugzilla.gnome.org/show_bug.cgi?id=761312
The client and compositor share access to the window
pixel buffers. After the client hands off (commits)
the buffer to the compositor it's not supposed to write
to it again until it's released by the compositor.
The code tries to deal with this contention by allocating
a temporary buffer and using that in the mean time. This
temporary buffer is allocated by a higher layer of the code
when begin_paint returns TRUE. Unfortunately, that layer of
the code has no idea when the buffer is released, so it ends
up blitting the temporary buffer back to the shared buffer
prematurely.
This commit changes begin_paint to always return FALSE.
A future commit will address the contention problem in
a different way.
https://bugzilla.gnome.org/show_bug.cgi?id=761312
There are a few places where we destroy a cairo surface and
then nullify it. This commit changes those to use
g_clear_pointer instead.
It also drops a cairo_surface_finish call that is unnecessary
https://bugzilla.gnome.org/show_bug.cgi?id=761312
The name surface is really overloaded when dealing
with wayland windows.
To alleviate ambiguity, this commit changes the name
of the "surface" and "subsurface" members to have
a wl_ prefix.
https://bugzilla.gnome.org/show_bug.cgi?id=761312
The fallback behaviour of get_work_area () divides the
screen width and height by the window scaling factor, but
those values are already scaled down.
https://bugzilla.gnome.org/show_bug.cgi?id=761474
Set _GTK_THEME_VARIANT to empty string when default theme variant
is used. This will allow to understand whether _GTK_THEME_VARIANT
is not supported or default variant is requested.
https://bugzilla.gnome.org/show_bug.cgi?id=761476
Temp windows without parent are used frequently in our testsuite;
using g_warning on them causes the tests to fail, which is not
useful. Reduce the warning to a g_message.
Presently, Gtk will only send a startup notification completion message
for the first window that is shown. This is not good for the case of
GtkApplication, where we are expected to participate in
startup-notification for all windows.
We have avoided this problem by manually emitting the startup complete
message from after_emit in GtkApplication.
Unfortunately, this causes problems for windows that are shown with a
delay. It is also a dirty hack.
The reason for the original behaviour is simple: there is a static
boolean in gtkwindow.c which controls it. We remove this.
Instead, clear the startup notification ID stored in GDK when sending
the completion message. GtkApplication will re-set this the next time
an event comes in which needs startup-notification handling. In the
non-GtkApplication case, newly shown windows will still not send the
message, since the cookie will have been cleared.
Finally, we remove the hack from GtkApplication's after_emit.
This will probably cause some regressions in terms of lingering startup
notification messages. The correct solution here is to always use
gtk_window_present(), including when merely opening a new document (with
a new tab, for example).
https://bugzilla.gnome.org/show_bug.cgi?id=690791
This was a thinko - what we sometimes do for signal names is to
use I_() to intern them (to avoid a strdup), but I_() is not
currently available in gdk, so lets just skip this
microoptimization for now.
It looks like the gnome-continuous headers haven't quite
caught up yet, so try __NR_memfd_create instead.
If that doesn't work, i'll likely just add in a fallback
code path.
The tmpdir is used for a wide assortment of things, and
can easily fill up. If it fills then desktop will start
crashing with SIGBUS errors.
This commit changes the shm pool allocation code, to use
memfd_create, instead, so the shared memory files will
be anonymous and not associated with /tmp
https://bugzilla.gnome.org/show_bug.cgi?id=761095
create_shm_pool doesn't need the width or height, it just needs
the total size. By passing it in, we're requiring it to redo
stride calculation unnecessarily.
This commit drops the width and height parameters and makes the
function just take the total size directly.
https://bugzilla.gnome.org/show_bug.cgi?id=760897
Right now, we assume the stride for the image surface needs to
be 4 byte aligned. This is, in fact, true, but it's better to
ask cairo for the alignment requirement directly rather than
assume we know the alignment rules.
This commit changes the code to use cairo_format_stride_for_width
to calculate a suitable rowstride for pixman.
https://bugzilla.gnome.org/show_bug.cgi?id=760897
create_shm_pool unlinks the temporary file a little,
too late. It should be unlinked before ftruncate()
is called for two reasons:
1) if ftruncate fails, the file is currently not
getting cleaned up at all
2) in theory, if the file is public some other process
could muck with it
This commit just moves the unlink call a little higher
up.
https://bugzilla.gnome.org/show_bug.cgi?id=760897
This function does not ignore empty rectangles. Since this
is a fairly subtle point about the behavior, it is worth
spelling this out in the documentation. We've had a bug
open about this for a long time:
https://bugzilla.gnome.org/show_bug.cgi?id=464528
These functions will be automatically called by the windowing backend.
The usual hooks to run this from in gtk/ shouldn't even happen, but
it is worth to document which calls are expected and which aren't.
If the grab window is destroyed the grab will be implicitly removed,
although we won't get GdkSeat:ungrab called in order to clear our
internal window<->seat relation entirely. Setting a weak ref will
nullify the pointer we keep on the seat to the window, avoiding the
expected crashes.
Due to implicit grabs, we basically can guarantee that the pointer
won't have any buttons pressed at the time of wl_pointer.enter.
Seems like a good place to unset any button modifiers that might
have been left stale by compositor grabs.
This includes managing input events and source-side DND events,
as well as setting the appropriate cursor and emitting the signals
that are expected in this mode of operation.
This function (most similar to gtk_drag_get_cursor() helps figure out
the right cursor that applies to a given action. To be used by the
various backends.
We've traditionally left GTK+ to handle the input side of things,
letting GDK only manage the windowing-specific messaging. This
way of splitting responsibilities is not compatible however with
some backends, we must fold then input management at the DnD stage
into GDK (and backends) domain.
The gdk_drag_context_manage_dnd() call is meant to be the entry
point for this mode of operation, if the drag and drop operation
becomes managed, the caller (i.e. gtkdnd.c) doesn't need to perform
grabs, nor manage input events itself.
As a consequence of this, different aspects now belong to the
backend GdkDragContext implementation:
- Because the caller doesn't see keyboard events anymore,
keyboard navigation must be managed in GDK, so is the decision
of the current action based on modifiers/button pressed.
- Because the caller won't see input events in general, the lifetime
of the drag and drop operation is now communicated through the
::drop-performed, ::dnd-finished and ::cancel events
- Because the caller doesn't participate anymore on the action
being chosen, the pointer cursor must be set by the backend.
The caller is rather notified of the final action through the
::action signal.
The caller is still responsible of dealing with the corresponding
GdkSelection, ensuring its ownership and communicating the supported
mimetypes.
And use it to handle kinetic scrolling in the GtkScrolledWindow.
However, dropping the delta check causes the X11-based kinetic
scroll to break since we don't have the stop event here. Correct handling of
xf86-input-libinput-based scroll events is still being discussed.
https://bugzilla.gnome.org/show_bug.cgi?id=756729
This adds support for the new wl_pointer events available in v5.
The wl_pointer.axis_source events can be ignored for the purposes here, the
main reason they exist is so that the combination of axis_source=finger and
axis_stop triggers kinetic scrolling. We don't need to care about the source,
axis_stop is enough for us to tell us when we're scrolling.
The wl_pointer.frame events group events together and is intended as a
mechanism to coalesce events together. This for example allows us to now
send a single GTK scroll event for a diagonal scroll. Previously, the two
wl_pointer.axis events had to be handled separately.
The wl_pointer.axis_discrete event sends mouse wheel clicks where
appropriate, and is translated into up/down/left/right scroll events.
https://bugzilla.gnome.org/show_bug.cgi?id=756729
This prevents WM from drawing shadows around tooltip windows,
which, in Adwaita, should have no shadow and are CSD-ish (which means
that tooltip window is larger than it looks, and WM draws the shadow
only on the outside, leaving a gap between the visible tooltip edge and
the shadow).
https://bugzilla.gnome.org/show_bug.cgi?id=759898
When a cursor is specified in gdk_seat_grab(), the cursor is reverted as
soon as the pointer enters or leaves another window.
To avoid this issue, store the grab cursor separately, so we force-apply
it in ::set_window_cursor(). Also, unset early the seat info from the
window on gdk_seat_ungrab(), so the next time switch_to_pointer_grab()
happens we end up picking the cursor set for the window underneath the
pointer window.
Based on a patch by Olivier Fourdan <ofourdan@redhat.com>.
https://bugzilla.gnome.org/show_bug.cgi?id=760213
We are getting the mime data destroy notify called when we
destroy the surface in finalize. Trying to set the XSync counters
at this time is a) pointless and b) yielding an X error because
the counters have already been destroyed.
To avoid this, unhook the damage tracking before destroying
the surface.
https://bugzilla.gnome.org/show_bug.cgi?id=760188
We are setting mime data with a destroy notify on the cairo
surface to get notified when cairo registers damage for the
surface (in that case, it clears the mime data, calling the
destroy notify). Unfortunately, the destroy notify is also
called when we remove the mime data ourselves, which was
not intentional.
Use a flag in the window impl struct to ignore the callback
when we are clearing the hook.
Instead of creating an intermediate pixbuf, just render
the window surface onto the new surface. Doing things this
way lets us avoid the cairo_surface_mark_dirty() call in
gdk_pixbuf_get_from_window(), which is not generally safe
to call on 'random' surfaces - it asserts that the surface
has no mime data attached, and the X11 backend uses mime
data for damage tracking purposes...
We destroy the widget that is wrapped around the drag window
when the object data on the drag context gets cleared. Destroying
the window before that happens leads to unpleasantries. E.g. we may
try to access the frame clock, which doesn't exist anymore, and
things go downhill from there. So, keep the window alive for
a little longer.
We destroy the widget that is wrapped around the drag window
when the object data on the drag context gets cleared. Destroying
the window before that happens leads to unpleasantries. E.g. we may
try to access the frame clock, which doesn't exist anymore, and
things go downhill from there. So, keep the window alive for
a little longer.
X11 has the notions of "transient for group", and while it's an ICCCM
violation, it's commonly used and documented that a window manager
would treat a window with transient_for set to None to transient for all
windows of its group.
gtk uses this when an application sets a dialog type window but does not
specify an explicit transient.
While this works on X11, there is no such thing as groups in Wayland and
the closest equivalent which is set_parent() in xdg-shell takes only one
parent. This is what is used for modal dialogs.
To get something similar in behavior to what is available on X11, a
solution is to update the parent() of the dialogs without transient when
the active surface changes.
Bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=759161
Quite a few applications use GTK_WINDOW_POPUP to create various
temporary windows and place then on screen. That works fine on X11 but
on Wayland there is no global coordinate system for regular surfaces.
If the application is using a gdk temp window and set a parent with
gtk_window_transient_for(), the gdk wayland backend has all it needs to
create a subsurface that can be placed at will by the application.
Bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=759738
Always returning a left_ptr if we can't find anything better
broke firefox application-specific fallback for missing cursors.
Keep that working by only doing the fallback for the CSS cursor
names, not for things like hashes.
https://bugzilla.gnome.org/show_bug.cgi?id=760141
Always returning a left_ptr if we can't find anything better
broke firefox application-specific fallback for missing cursors.
Keep that working by only doing the fallback for the CSS cursor
names, not for things like hashes.
https://bugzilla.gnome.org/show_bug.cgi?id=760141
Functions requiring CoInitialize are called just in two places:
- the filechooser thread which calls its own CoInitializeEx
- the dnd code
Moving CoInitialize in the dnd specific init is cleaner and
we can pair it with the corresponding CoUninitialize since
CoUninitialize should be called as many times as CoInitialize.
Note that it is ok to call this function multiple times, so it
will not break if another codepath will need it in the future.
The patch also replaces the deprecated CoInitialize with the
equivalent call to CoInitializeEx (already used in the filechooser).
In most places, we can do with the pointer/keyboard of the default seat
instead of the client pointer. We can also remove some code from
gdk_input_init() because we know for sure there's no floating devices to
care about here.
There's places where we still need to deal with floating devices, which are
unseen by seats. Ignore deprecations and keep using GdkDeviceManager until
we can forget about floating devices.
There's places where we still need to deal with floating devices, which are
unseen by seats. Ignore deprecations and keep using GdkDeviceManager until
we can forget about floating devices.
There's places where we still need to deal with floating devices, which are
unseen by seats. Ignore deprecations and keep using GdkDeviceManager until
we can forget about floating devices.
There's places where we don't set a seat yet, plus the places
outside GTK+ where events are created, we should warn and fall
back to the master device seat with these.
Gdk Wayland backend walks up the transient windows tree, but does not
check for cycles when doing so.
As a result, if two or more windows are transient to each other, the
Wayland gdk backend will enter an infinite loop.
While this is clearly a bug in the application, gtk+/gdk should be more
robust and handle such errors more gracefully.
To avoid looping infinitely at various point in the code, check for a
possible loop when setting the transient relationship and deny the
request to set a window transient for another if that would create a
loop.
Bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=759299
