Somebody could do:
$ mv my-evil-program mutter-wayland
$ PATH=.:$PATH mutter-launch mutter-wayland
It's not secure, and it's hard to test with, so just drop it for now
We'll be relying on logind to hand us permissions in the future.
We require a MetaWindow to properly implement some of the requests
for xdg_surface, so add a way to have an unmapped MetaWindow that
we can store properties on, that we later map when the client
attaches a buffer...
The compiler is not quite smart enough to figure out that the condition
for setting the "compositor" variable matches a later condition for
accessing it, so express this in a way the compiler will understand.
For clarity, rename meta_window_get_outer_rect() to match terminology
we use elsewhere. The old function is left as a deprecated
compatibility wrapper.
Instead of passing around MetaFrameBorders, compute it when we need it.
This also allows us to know that we are using MetaFrameBorders only for windows
with frames (where it is meaningful) and not for frameless windows, which
can have custom borders which we need to interpret differently.
https://bugzilla.gnome.org/show_bug.cgi?id=707194
Cache the computed border size so we can fetch the border size at
any time without worrying that we'll be spending too much time in
the theme code (in some cases we might allocate a PangoFontDescription
or do other significant work.)
The main effort here is clearing the cache when various bits of window
state change that could potentially affect the computed borders.
https://bugzilla.gnome.org/show_bug.cgi?id=707194
There are extensive places in the code where we convert between the client
rectangle and the frame rectangle. Instead of manually doing it use
new helper functions on MetaWindow and the existing meta_window_get_outer_rect().
This fixes a number of bugs where the computation was being done incorrectly,
most of these bugs are with the recently added custom frame extents, but
some relate to invisible borders or even simply to confusion between the
window and frame rectangle.
Switch the placement code to place the frame rectangle rather
than the client window - this simplifies things considerably.
https://bugzilla.gnome.org/show_bug.cgi?id=707194
What we want to achieve is that the dialog is visually centered
on the parent, including the decorations for both, and making sure
that CSD/frame_extents are respected.
https://bugzilla.gnome.org/show_bug.cgi?id=707194
Use the "hotplug_mode_update" connector property indicating that the
screen settings should be updated: get a new preferred mode on hotplug
events to handle dynamic guest resizing (where you resize the host
window and the guest resizes with it).
https://bugzilla.gnome.org/show_bug.cgi?id=711216
Clients like on-screen keyboards try not to take focus when the user clicks
on their window by setting the Input hint to false. However, due to GTK+ and
GDK bugs, the public API for setting the Input hint to false don't remove
WM_TAKE_FOCUS from WM_PROTOCOLS, unintentionally putting them into Globally
Active mode.
These clients also expect that since they don't want to take focus, they want
the focus to remain on the existing window. In this case, for clients like
on-screen keyboards, it's so they can send synthesized keyboard events to the
focused window.
https://bugzilla.gnome.org/show_bug.cgi?id=710296
Since this is stored in an array full of data that will be copied
around, we can't rely on pointer addresses for every item in a stack
not changing.
I don't see any reason that we even have a weak pointer, either.
This code looks safe to me without it.
When a Wayland compositor, simply rely on the clutter actor allocation
changed signal to sync geometry and emit window actor size changed
signals.
Attaching a wl_buffer to a MetaShapedTexture will signal allocation
changed on the corresponding MetaSurfaceActor, which the MetaWindowActor
is listening to.
Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
https://bugzilla.gnome.org/show_bug.cgi?id=705502
Instead of having MetaWindowActor only have one single MetaShapedTexture
as actor drawing its content, introduce a new abstract MetaSurfaceActor
that takes care of drawing.
This is one step in the direction to decouple MetaWaylandSurface with a
MetaWindow and MetaWindowActor (except for shell/xdg surfaces) in order
to finally support subsurfaces like features, or any feature where
window is not drawn using a single texture.
The first step, implemented in this patch, is to not have
MetaWindowActor work directly with a shaped texture. There are still
some cases where it simply gets the texture and goes on as before, but
this should be changed by either removing the need of going via
MetaWindowActor or by adding some generic interface to MetaSurfaceActor
that doesn't limit its functionality to one shaped texture.
There should be no visible difference nor after this patch, but
meta_window_actor_get_texture() and meta_surface_actor_get_texture()
should be deprecated when equivalent functionality has been introduced.
Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
https://bugzilla.gnome.org/show_bug.cgi?id=705502
Rather than have MetaWaylandSeat do all the state management itself,
put the split between the root cursor and the window cursor in the
cursor tracker itself. We'll expand this to add a "grab" cursor in
the next commit, allowing us to force a cursor on grab operations.
In order to see all Clutter events, Mutter was previously installing a
signal handler on the ‘captured-event’ signal on the stage and
additionally using a signal emission hook to cope with grabs. This
changes it to use the new clutter_event_add_filter API so that we can
avoid the signal emission hook hack.
There is now a meta_display_handle_event alongside the
meta_display_handle_xevent function which handles events in terms of
Clutter events instead of X events. A Clutter event filter is
registered so that all Clutter events will pass through this function.
The pointer event handling code from the X event version has been moved
into this new function and has been modified to use the details from
the Clutter event instead of the X event. This is a step towards
moving all of the event handling code over to use Clutter events.
Based-heavily-on-a-patch-by: Neil Roberts <neil@linux.intel.com>
This helps with git's diff code by moving all the giant indentation
changes, letting us know what's going on better when we move to
Clutter for event handling.
The plan is to make a new version of meta_display_handle_event that
will accept Clutter events instead of X events and then gradually move
over the events to the new function and finally remove the X version.
When X clients change the keyboard map, the also update a property
on the root window. We can notice that and rebuild our data structures
with the new values, as well as inform the wayland clients.
This is a terrible hack, and it's not how we want to implement things
in 3.12, but it's enough to have the same keyboard layout in the
shell, in X clients and in wayland clients in 3.10, until we decide
on the fate of the keyboard g-s-d plugin.
https://bugzilla.gnome.org/show_bug.cgi?id=707446
According to the wayland spec (A.14.1.5. wl_surface::set_opaque_region),
setting a NULL opaque region is possible and should cause the pending
opaque region to be set to empty. This implements the required
behavoir.
Also fixes set_input_region, which suffered from an analogous bug.
Previously the weston-simple-egl demo client caused mutter-wayland to
crash with a segfault in meta_wayland_surface_set_opaque_region, with
this patch it works as intended.
https://bugzilla.gnome.org/show_bug.cgi?id=711518
Expose min-backlight-step so that gnome-settings-daemon can
support backlights with less than 10 steps without mutter
normalizing the brightness back to its original value
https://bugzilla.gnome.org/show_bug.cgi?id=710380
When creating MetaCursorReference using a wl_resource, use the provided
hotspot coordinates.
This makes clients such as clickdot work more correctly.
Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
https://bugzilla.gnome.org/show_bug.cgi?id=709593
The part of code dealing with move/resize grab in display.c is only
responsible of this behavior when triggered with a modifier. So it
shouldn't stop the move/resize behavior triggered from a mouse event
without modifier on the title bar or sides of the window.
https://bugzilla.gnome.org/show_bug.cgi?id=704759
The current time offset calculation is wrong. It is supposed to calculate
the offset between the current time and the
"time where it message should be sent" (last_time + interval).
Fix the math to actually do that.
https://bugzilla.gnome.org/show_bug.cgi?id=709340
Rather than do the cursor -> name translation ourselves in two different
places, use the facilities in libXcursor to do it for us. Put the shared
piece of code in meta-cursor-tracker, and use it for both server-side and
client-side cursor loading.
The destroy notify for a DBus watch holds a reference to the IdleMonitor,
but the IdleMonitorWatch object doesn't (it knows all watches will
be destroyed before the monitor is, so it doesn't need one). This
means that the DBus watch reference can be the only one keeping
the IdleMonitor alive (expecially true for device idle monitors,
which are only used by g-s-d/cursor), and that means that calling
the destroy notify freezes the monitor (and the next X calls
access garbage).
https://bugzilla.gnome.org/show_bug.cgi?id=708420
If you maximize a CSD window on a monitor without struts, it ends
up taking the whole monitor size, but it doesn't mean that the
application wants to fullscreen.
https://bugzilla.gnome.org/show_bug.cgi?id=708718
We must set x11_size_changed even if we are frozen, as every window
size change makes the X server drop the pixmap, and we might lose
the information at the next thaw() if the window changes size
twice in one frame (so we would keep drawing with the old pixmap
until something else causes another resize)
Need two passes, because the order we traverse the array is
alphabetical on connector name, not left to right, so we might
see a monitor on the right before we get the offset from disabling
the primary monitor.
https://bugzilla.gnome.org/show_bug.cgi?id=707473
No, holes in the framebuffer are not a good a thing: windows can
get lost there, and the user can get very confused.
Instead, compact the monitors that where previously after.
https://bugzilla.gnome.org/show_bug.cgi?id=707473
The XSync semantics mandate that alarms already expired will not
fire until the counter is reset and the alarm triggered again, so
clients traditionally called get_idle_time() first to see if they
should install the alarm.
This is inherently racy, as by the time the call is handled by
mutter and the reply received the idle time could be different.
Instead, if we see that the watch would have fired in the past,
fire it immediately.
This is a behavior change, but it's a compatible one, as all legacy
clients are calling get_idle_time() first, and it was perfectly
possible for the idle time counter to trigger the alarm right
after the get_idle_time() call.
https://bugzilla.gnome.org/show_bug.cgi?id=707302
Grabs are now slice allocated structures that are handled by
whoever starts the grab. They contain a generic grab structure
with the interface and a backpointer to the MetaWaylandPointer.
The grab interface has been changed to pass full clutter events,
which allowed to remove the confusion between grab->focus and
pointer->focus. Invidual grabs are now required to keep their
focus, and choose whoever gets the events.
https://bugzilla.gnome.org/show_bug.cgi?id=707863
Once the sizing is properly wired up, we need to make sure that
the size at the initial map is correct, and not always 0, 0 because
the buffer is not yet converted into a CoglTexture by MetaShapedTexture,
otherwise we end up sending out configure events at 1 x 1.
To do so, we cache the surface type in the initial state until the
first commit.
https://bugzilla.gnome.org/show_bug.cgi?id=707401
To properly resize clients, we need to send them configure events
with the size we computed from the constraint system, and
then check if the new size they ask is compatible with
our expectation.
Note that this does not handle interactive resizing yet, it
merely makes the API calls work for wayland clients.
https://bugzilla.gnome.org/show_bug.cgi?id=707401
Make sure that meta_display_list_windows() returns wayland windows
too, by keeping a separate hash for wayland clients.
This fixes a crash in the alt-tab code of gnome-shell.
Reviewed by drago01 in IRC.
If we skip getting the clip rectangle because we don't have an
allocation or a texture, don't intersect with the visible region.
This avoids a pixman warning of an invalid rectangle.
Reviewed by drago01 in IRC.
We don't have actual pointer barriers implemented, so this is a
quick workaround to trigger the fallback paths in the shell, for
the hot corner and the message tray.
To be reverted after 3.10
Not only this way we get the right Adwaita cursor as the default
(instead of shipping our own in png format), but we also add
support for all MetaCursors as root cursor (which most important
should allow us to have I-beams in shell entries)
https://bugzilla.gnome.org/show_bug.cgi?id=707573
Using the new Cogl API to actually modeset (because we can't
use the DRM API directly without controlling buffer swap), we
can finally have a KMS monitor backend, which means full display
configuration when running on bare metal.
https://bugzilla.gnome.org/show_bug.cgi?id=706308
The API was changed during the patch review.
(Yes, we were depending on API which was sitting in a patch not
yet reviewed... you know, vertical integration!)
https://bugzilla.gnome.org/show_bug.cgi?id=707929
At logout, we want to die when gnome-session tells us. Previously,
we were relying on the X server going down (killed by GDM at the
end of the session), but we can't use that in wayland.
https://bugzilla.gnome.org/show_bug.cgi?id=706421
Warnings that are going to the journal should be not translated:
they're not user visible, and translating them would just make
bug reporting harder (as now the developers need to understand
what the warning is saying)
https://bugzilla.gnome.org/show_bug.cgi?id=707897
Switching meta/util.h to gi18n.h was wrong, mutter is a library
and needs gi18n-lib.h, but that cannot be included from a public
header (since it depends on config.h or command line options),
so split util.h into a public and a private part.
https://bugzilla.gnome.org/show_bug.cgi?id=707897
Move the option from the mutter binary to libmutter, and
rename from --nested to --wayland.
This allows gnome-shell to drop the set_is_wayland_compositor()
call.
https://bugzilla.gnome.org/show_bug.cgi?id=707897
Add MIN(...) with the interface version actually implemented
to all resource constructor, so that we never risk seeing requests
we don't implement (and consequently segfault)
https://bugzilla.gnome.org/show_bug.cgi?id=707851
Replace the deprecated APIs with the modern variants (which
also give us full control on the versioning).
Also, note that we only support version 2 of wl_seat. Version
3 is for multiple pointer/keyboards for a client, but
we don't implement that yet. If a client requests version 3
of wl_seat or make a version 3 request, it will get a protocol error.
https://bugzilla.gnome.org/show_bug.cgi?id=707851
clutter_stage_show_cursor()/hide_cursor() only works in the X11
backend (where someone else is in charge of showing the cursor),
and even then, it has confusing effects when running nested wayland,
so an abstraction layer is needed.
https://bugzilla.gnome.org/show_bug.cgi?id=707474
We can't rely on clutter's xkb_state, because that's updated
when events are pulled from the kernel, not when we see them.
Instead, use the new clutter API to get the full modifier state
from the event (which, as a side effect, also works when clutter
is using the X11 backend for running nested).
https://bugzilla.gnome.org/show_bug.cgi?id=706963
We don't get notifications from X11 when the mode is reset, so
our cached value can get stale. To work around that, always forward
requests to the backend (and let it deal with ignoring the change
if wanted)
https://bugzilla.gnome.org/show_bug.cgi?id=707649
Use the new Clutter hook to make sure the pointer never enters
the dead area caused by the different monitor sizes.
You don't realize how much X is doing for you until you lose it...
https://bugzilla.gnome.org/show_bug.cgi?id=706655
The meta_create_texture_pipeline function used to create a dummy 1x1
texture so that it could make sure that the all of the state that
affects the shader generation would be set on the template pipeline so
that Cogl could share the pipeline's shader with any other pipelines
that are just rendering a texture. This is no longer necessary because
the only thing that affects the shader generation is the texture type,
not the actual texture data and Cogl now has a function to explicitly
set the texture type which we can use instead. Additionally even if
the template mechanism is not used at all Cogl will still end up
reusing the same shader because it now has a shader cache which is
indexed by the pipeline state so pipeline's don't strictly need to
share ancestry in order to take advantage of it. However we still
might as well use the function because if there is a common ancestry
it is faster to look up the shader because Cogl doesn't need to hash
the pipeline state.
https://bugzilla.gnome.org/show_bug.cgi?id=707458
(cherry picked from commit c5bf60eab4)
Add a new interface, gtk_shell, than can be used by gtk to
retrieve a surface extension called gtk_surface, which will be
used to communicate with mutter all the GTK extensions to EWMH
https://bugzilla.gnome.org/show_bug.cgi?id=707128
Add support for GTK application menus
To do so, we need to be able to set surface state before creating
the MetaWindow, so we introduce MetaWaylandSurfaceInitialState as
a staging area.
The gtk-shell-surface implementation would either write to the
initial state, or directly to the window.
At the same, implement set_title and set_class too, because it's
easy enough.
https://bugzilla.gnome.org/show_bug.cgi?id=707128
According to the wayland documentation, damage outside the
window size is ignored.
This happened with xwayland+wlshm (causing a GL error when calling
TexSubImage2D), probably due to not resizing the buffer
until we receive the corresponding X event.
Might also be an off-by-one in xwayland, as the window size did
not actually change.
Note: we might want to take the configure_notify path instead,
and keep the GL/clutter size consistent with wayland rather than
X, because in the end that's what matters for events and composition.
https://bugzilla.gnome.org/show_bug.cgi?id=706289
If, checking the event timestamps, we see that a new configuration
was explicitly requested by an another XRandR client, don't proceed to
apply the intended configuration again, even if looking at the
EDIDs it appears that the outputs changed.
This works around some buggy Xorg drivers (qxl, vbox) that generate
a new serial number everytime the user resizes the host window.
https://bugzilla.gnome.org/show_bug.cgi?id=706735
device_id_max is set to the device_id in ensure_device_monitor(), but we
will loop only to (device_id_max - 1) when propagating the sync XEvent
down, missing the device correspondng to device_id_max.
https://bugzilla.gnome.org/show_bug.cgi?id=707250
The protocol specification says that opaque / input regions should be
considered pending state and should only be actually swapped out when
the surface is committed, so it can be set atomically.
We had an assertion in meta_wayland_surface_free() that after
a repick() we would not choose the freed surface, but that didn't
consider surfaces destroyed while holding the implicit pointer
grab (ie, because the user clicked on the X button). In that case,
we need to bypass the grab infrastructure and explicitly unfocus
the dead surface.
https://bugzilla.gnome.org/show_bug.cgi?id=706982
After a MetaWaylandSurface is associated with a MetaWindow, it
should be freed only when the MetaWindow is unmanaged. For wayland
clients, the window is unmanaged when the resource is destroyed,
but for X11 clients we want to wait for the unmap event.
https://bugzilla.gnome.org/show_bug.cgi?id=705917
Calling XIGrabDevice has no effect under wayland, because the
xserver is getting events from us. Instead, we need to use our
own interfaces for grabs.
At the same time, we can simplify the public API, as plugins
should always listen for events using clutter.
https://bugzilla.gnome.org/show_bug.cgi?id=705917
We need to track the full xkb_state to have the necessary information
to send to the clients, otherwise they may get confused and lock
or invert the modifiers. In the evdev backend, we just retrieve the
same state object that clutter is using, while in the other backends
we fake the state using what clutter is providing (which is a subset
of what X11 provides, which would be necessary to have full state)
https://bugzilla.gnome.org/show_bug.cgi?id=705862
Once mutter is started from weston-launch on its own VT, there is
no way to change VT again (for example to actually start an application),
because the keyboard is put in raw mode.
So introduce some keybindings mimicking the standard X ones (Ctrl+Alt+Fn)
that switch the VT manually when activated.
https://bugzilla.gnome.org/show_bug.cgi?id=705861
Now that we have a setuid launcher binary, we can make use of
using a private protocol through the socket we're passed at startup.
We also use the new hook in clutter-evdev to ask mutter-launch for
the FDs of the input devices we need, and we emulate the old X
DRM lock with a nested GMainContext without sources.
In the future, mutter-launch will be replaced with the new logind
API currently in development.
https://bugzilla.gnome.org/show_bug.cgi?id=705861
Set the TTY mode appropriately at startup, and clean it up
when the compositor exits. Also, take control of VT switching,
including the calls to drmSetMaster and drmDropMaster as appropriate.
In the future, we the kernel implements the mute evdev ioctl,
we'll also make sure that input devices are appropriately released.
https://bugzilla.gnome.org/show_bug.cgi?id=705861
Being a setuid binary, our LD_LIBRARY_PATH is cleared by glibc at
startup, but we need the spawned binary to see it, otherwise
jhbuild doesn't work, so hardcode it using the configured libdir.
https://bugzilla.gnome.org/show_bug.cgi?id=705861
Remove the ability to launch as a different user, which we don't
need because we're spawned by gdm or by the user manually on the
command line.
At the same time, require an active local session, and remove
the ability to run from anywhere by being in the right user group
(which automatically gives you root-like privileges)
https://bugzilla.gnome.org/show_bug.cgi?id=705861
To run mutter as a display server, one needs to acquire and
release the DRM master, which is only possible for root, so
we take advantage of weston-launch, a small setuid helper binary
written for the weston project. We import our own slightly
modified copy of it, because weston-launch only launches weston,
for security reasons.
https://bugzilla.gnome.org/show_bug.cgi?id=705861
We must send frame_drawn and frame_timing messages to even when
we don't actually queue a redraw on screen to comply with the
WM sync spec.
So throttle such apps to down to a ~100ms interval.
https://bugzilla.gnome.org/show_bug.cgi?id=703332
When we get a damage event we update the window by calling
meta_shaped_texture_update_area which queues a redraw on the actor.
We can avoid that for obscured regions by comparing the damage area to
our visible area.
This patch causes _NET_WM_FRAME_DRAWN messages to be not sent in some cases
where they should be sent; they will be added back in a later commit.
https://bugzilla.gnome.org/show_bug.cgi?id=703332
When drawing entirely opaque regions, we traditionally kept blending on
simply because it made the code more convenient and obvious to handle.
However, this can cause lots of performance issues on GPUs that aren't
too powerful, as they have to readback the buffer underneath.
Keep track of the opaque region set by windows (through _NET_WM_OPAQUE_REGION,
Wayland opaque_region hints, standard RGB32 frame masks or similar), and draw
those rectangles separately through a different path with blending turned off.
https://bugzilla.gnome.org/show_bug.cgi?id=707019
Split out pipeline creation to a separate function so that we don't
have so much dense code in the paint function itself, and remove some
indentation levels.
Also, don't use our own template for the unmasked pipeline, since it
has nothing different from the default pipeline template.
We also don't store the pipelines anymore since their creation isn't
really helping us; we set the mask texture and paint texture on every
paint anyway.
https://bugzilla.gnome.org/show_bug.cgi?id=707019
We need to track the full xkb_state to have the necessary information
to send to the clients, otherwise they may get confused and lock
or invert the modifiers. In the evdev backend, we just retrieve the
same state object that clutter is using, while in the other backends
we fake the state using what clutter is providing (which is a subset
of what X11 provides, which would be necessary to have full state)
https://bugzilla.gnome.org/show_bug.cgi?id=705862
The user active watch is a one-fire watch, but it is valid in the API
for the callback to explicitly remove the watch itself. In that case,
the watch will be invalid after the user removes it, and the memory
potentially freed. So make sure to not dereference the watch after
the callback is called.
https://bugzilla.gnome.org/show_bug.cgi?id=706825
Dialogs that don't have a parent should not be skip-taskbar,
otherwise they get lost and there is no way to recover them
(because they're not autoraised when activating the parent),
but toolkits and applications set the hint anyway.
https://bugzilla.gnome.org/show_bug.cgi?id=673399
Modify all visible instances of mutter with mutter-wayland
(libraries, folders, pkgconfig, etc.), so that the wayland
branch can be installed alongside the usual X11 mutter.
https://bugzilla.gnome.org/show_bug.cgi?id=705497
In the wayland branch of mutter, we want to build a wayland version
of the mutter libraries, and that's much easier if we just build
wayland support unconditionally.
The define is kept to avoid a huge diff, but should be removed
in a later patch.
Also, wayland support can still be disable at runtime, by
launching mutter without the --nested switch.
https://bugzilla.gnome.org/show_bug.cgi?id=705497
If we're attempting to reconfigure the CRTCs to the same parameter,
skip the X call, as in some drivers a modeset can take time and
cause flicker.
https://bugzilla.gnome.org/show_bug.cgi?id=706672
To allow other clients (gnome-session, gnome-settings-daemon)
to monitor user activity, introduce a DBus interface for the
idle monitor inside mutter.
https://bugzilla.gnome.org/show_bug.cgi?id=706005
When running as a wayland compositor, we can't use the xserver's
IDLETIME, because that's updated only in response to X events.
But we have all the events ourselves, so we can just run the timer
in process.
https://bugzilla.gnome.org/show_bug.cgi?id=706005
We can't use the X11 stage window, if clutter is not using the X11
backend (and even if it was, it would be bogus when the xwayland
server is not the one clutter is talking to). Instead, we introduce
the concept of "focus type", which we use to differentiate the
various meanings of None in the focus_xwindow field.
https://bugzilla.gnome.org/show_bug.cgi?id=706364
Remove grab window and cursor from the API, and just grab always
on the stage window with no cursor.
This is mainly to remove the X11 usage in the public API, in preparation
for implementing this in wayland.
https://bugzilla.gnome.org/show_bug.cgi?id=705917
Using out-of-band notifications from the wayland protocol or from
X is racy, in that the client could ask for the new resources before
we have them.
Instead, with a signal, we are sure that when the client asks for
it, it will get the right values.
https://bugzilla.gnome.org/show_bug.cgi?id=706382
Under X, we need to use XFixes to watch the cursor changing, while
on wayland, we're in charge of setting and painting the cursor.
MetaCursorTracker provides the abstraction layer for gnome-shell,
which can thus drop ShellXFixesCursor. In the future, it may grow
the ability to watch for pointer position too, especially if
CursorEvents are added to the next version of XInput2, and thus
it would also replace the PointerWatcher we use for gnome-shell's
magnifier.
https://bugzilla.gnome.org/show_bug.cgi?id=705911
