This allows us to look for a match with an O(1) search instead of O(n)
which is nice, particularly when running as a wayland compositor in
which case we have to do this search for every key press event (as
opposed to only when our passive grab triggers in the X compositor
case).
We actually need two hash tables. On one we keep all the keybindings
themselves which allows us to add external grabs without constantly
re-allocating the array we were using previously.
The other hash table is an index of the keybindings in the first table
by their keycodes and mask which is how we actually match the key
press events. This second table thus needs to be rebuilt when the
keymap changes since keycodes have to be resolved then but since we're
only keeping pointers to the first table it's a fast operation.
https://bugzilla.gnome.org/show_bug.cgi?id=725588
Instead of looping over an array of keybindings to find the correct
binding, just use display_get_keybinding().
In the next commit, we'll change the array to be a hash map, so this
helps the patch be cleaner.
https://bugzilla.gnome.org/show_bug.cgi?id=725588
We don't want to match the keysym so that e.g. an accelerator
specified as "<Super>a" works if the current keymap has a keysym other
than 'a' for that keycode which means that the accelerator would
become inaccessible in a non-latin keymap.
This is inconvenient for users that often switch keyboard layouts, or
even have different layouts in different windows, since they expect
system-level keybindings to not be affected by the current layout.
https://bugzilla.gnome.org/show_bug.cgi?id=678001
The only events we handle as XIEvents are FocusIn/Out, Enter and
Leave. Motion, ButtonPress/Release, KeyPress/Release are handled
through clutter instead.
Among other things, this means we don't need to fake motion compression
by peeking over gdk event queue...
Mouse event handling was duplicated, resulting in weird interactions
if clutter was allowed to see certain events (for example under
wayland, where it gets all events). Because now clutter sees all
X events, even when running as an x11 compositor, we can handle
everything using the clutter variants.
At the same time, rewrite a little the passive button grab code,
to make it clear what is being matched on what and why.
We must spoof events to clutter even if they are associated
with a MetaWindow, because keyboard events are always associated
with one (the focus window), and we must process keybindings
for window togheter with the global ones if they include Super,
because we're not going to see them again.
... and individually. It turns out that updating the opaque region
was causing the shape region to be updated, which was causing a new
shape mask to be generated and uploaded to the GPU. Considering
GTK+ regenerates the opaque region on pretty much any focus change,
this is not good.
The handler pointer is dangling in MetaKeyBinding until
rebuild_key_binding_table() is run, so we can't dereference it.
Because we only need the flags at ungrab time, store a copy
in the MetaKeyBinding structure.
https://bugzilla.gnome.org/show_bug.cgi?id=724402
For decorated windows, we don't want to apply any input
shape, because the frame is always rectangular and eats
all the input.
The real check is in meta-window-actor, where we consider
if we need to apply the bounding shape and the input shape
(or the intersection of the two) to the surface-actor,
but as an optimization we avoid querying the server in
meta-window.
Additionally, for undecorated windows, the "has input shape"
check is wrong if the window has a bounding shape but not an
input shape.
It triggers too often, making G_DEBUG=fatal-warnings quite useless.
Owen is going to rewrite this code sometime in the near future, so
I'm just gonna kill this warning for now.
If the last reference of a MetaIdleMonitor is held by the caller, it may
happen that the last reference is lost when calling the GDestroyNotify,
if this happens when the watched DBus name vanishes, the object (and the
watches hashtable) are destroyed while manipulating the watches hashtable,
so bad things may happen then.
Fix this by wrapping the operation by a ref/unref pair, so the object would
be destroyed after operating on the hashtable.
https://bugzilla.gnome.org/show_bug.cgi?id=724969
The rendering logic before was somewhat complex. We had three independent
cases to take into account when doing rendering:
* X11 compositor. In this case, we're a traditional X11 compositor,
not a Wayland compositor. We use XCompositeNameWindowPixmap to get
the backing pixmap for the window, and deal with the COMPOSITE
extension messiness.
In this case, meta_is_wayland_compositor() is FALSE.
* Wayland clients. In this case, we're a Wayland compositor managing
Wayland surfaces. The rendering for this is fairly straightforward,
as Cogl handles most of the complexity with EGL and SHM buffers...
Wayland clients give us the input and opaque regions through
wl_surface.
In this case, meta_is_wayland_compositor() is TRUE and
priv->window->client_type == META_WINDOW_CLIENT_TYPE_WAYLAND.
* XWayland clients. In this case, we're a Wayland compositor, like
above, and XWayland hands us Wayland surfaces. XWayland handles
the COMPOSITE extension messiness for us, and hands us a buffer
like any other Wayland client. We have to fetch the input and
opaque regions from the X11 window ourselves.
In this case, meta_is_wayland_compositor() is TRUE and
priv->window->client_type == META_WINDOW_CLIENT_TYPE_X11.
We now split the rendering logic into two subclasses, which are:
* MetaSurfaceActorX11, which handles the X11 compositor case, in that
it uses XCompositeNameWindowPixmap to get the backing pixmap, and
deal with all the COMPOSITE extension messiness.
* MetaSurfaceActorWayland, which handles the Wayland compositor case
for both native Wayland clients and XWayland clients. XWayland handles
COMPOSITE for us, and handles pushing a surface over through the
xf86-video-wayland DDX.
Frame sync is still in MetaWindowActor, as it needs to work for both the
X11 compositor and XWayland client cases. When Wayland's video display
protocol lands, this will need to be significantly overhauled, as it would
have to work for any wl_surface, including subsurfaces, so we would need
surface-level discretion.
https://bugzilla.gnome.org/show_bug.cgi?id=720631
The input region was set on the shaped texture, but the shaped texture
was never picked properly, as it was never set to be reactive. Move the
pick implementation and reactivity to the MetaSurfaceActor, and update
the code everywhere else to expect a MetaSurfaceActor.
I implemented pinging, but never actually enabled the feature
properly on Wayland surfaces by setting the net_wm_ping hint to
TRUE, causing the fallback path to always be hit.
Rename net_wm_ping to can_ping so it doesn't take on an
implementation-specific meaning, and set it for all Wayland windows.
To prevent the MetaSurfaceActor from being destroyed, we normally
unparent it before we unmanage the window. However, this doesn't
work for XWayland windows, which we unmanage when we get UnmapNotify
or DestroyNotify, not when we get the wl_surface_destroy.
To solve this, add an early hook in meta_window_unmanage that
unparents the surface actor if we have one. At the same time, clean
up the destruction code to remove old comments and assumptions about
how wl_shell behaves.
This was a bad idea, as ping/pong has moved to a client-specific
request/event pair, rather than a surface-specific one. Revert
the changes we made here and correct the code to make up for it.
This reverts commit aa3643cdde.
If we fail to find the IDLETIME counter, then the alarm variable will be
uninitialised. Most code paths are careful to check this before
submitting XSync calls, but there is one check missing.
https://bugzilla.gnome.org/show_bug.cgi?id=724364
In order for the compositor to properly determine whether a client
is an X11 client or not, we need to wait until XWayland calls
set_window_id to mark the surface as an XWayland client. To prevent
the compositor from getting tripped up over this, make sure that
the window has been fully initialized by the time we call
meta_compositor_add_window.
https://bugzilla.gnome.org/show_bug.cgi?id=720631
Traditionally, WMs unmap windows when minimizing them, and map them
when restoring them or wanting to show them for other reasons, like
upon creation.
However, as metacity morphed into mutter, we optionally chose to keep
windows mapped for the lifetime of the window under the user option
"live-window-previews", which makes the code keep windows mapped so it
can show window preview for minimized windows in other places, like
Alt-Tab and Expose.
I removed this preference two years ago mechanically, by removing all
the if statements, but never went through and cleaned up the code so
that windows are simply mapped for the lifetime of the window -- the
"architecture" of the old code that maps and unmaps on show/hide was
still there.
Remove this now.
The one case we still need to be careful of is shaded windows, in which
we do still unmap the client window. In the future, we might want to
show previews of shaded windows in the overview and Alt-Tab. In that
we'd also keep shaded windows mapped, and could remove all unmap logic,
but we'd need a more complex method of showing the shaded titlebar, such
as using a different actor.
At the same time, simplify the compositor interface by removing
meta_compositor_window_[un]mapped API, and instead adding/removing the
window on-demand.
https://bugzilla.gnome.org/show_bug.cgi?id=720631
Prior to the DisplayConfig merge, we would set _NET_WM_FULLSCREEN_MONITORS
to (unsigned)-1 when unset. After that, we would have invalid
reads inside meta_screen_monitor_index_to_xinerama_index() (called
with -1).
The way I read the specification, the proper way to indicate
that the window is back to fullscreen on all monitors is to
remove the property, so do that.
Also, add an assertion that meta_screne_monitor_index_to_xinerama_index()
is doing the right thing.
https://bugzilla.gnome.org/show_bug.cgi?id=724258
The code that prevents the creation of multiple MonitorInfos for clones
wasn't working due to using the wrong index when getting the already
created info so fix that to use the correct one.
https://bugzilla.gnome.org/show_bug.cgi?id=710610
Use our new "surface_mapped" field to delay the showing of XWayland clients
until we have associated together the window's XID and the Wayland surface ID.
This ensures that when we show this window to the compositor, it will properly
use the Wayland surface for rendering, rather than trying to use COMPOSITE and
crash.
https://bugzilla.gnome.org/show_bug.cgi?id=720631
The goal here is to make MetaWindow represent a toplevel, managed window,
regardless of if it's X11 or Wayland, and build an abstraction layer up.
Right now, most of the X11 code is in core/ and the wayland code in wayland/,
but in the future, I want to move a lot of the X11 code to a new toplevel, x11/.
X11 window frames use special UI grab ops, like META_GRAB_OP_CLICKING_MAXIMIZE,
in order to work properly. As the frames in this case are X11 clients, we need
to pass through X events in this case. So, similar to how handle_xevent works,
use two variables, bypass_clutter, and bypass_wayland, and set them when we
handle specific events.
Using a full InputOutput window causes us to make a full Wayland surface
for it, and go through the X server. As the goal of the guard window is
a window for us to stack minimized windows under so we can prevent them
from getting input, it makes sense to use an InputOnly window here.
We no longer unmap the toplevel windows during normal operation. The
toplevel state is tied to the window's lifetime.
Call meta_compositor_add_window / meta_compositor_remove_window instead...
Traditionally, WMs unmap windows when minimizing them, and map them
when restoring them or wanting to show them for other reasons, like
upon creation.
However, as metacity morphed into mutter, we optionally chose to keep
windows mapped for the lifetime of the window under the user option
"live-window-previews", which makes the code keep windows mapped so it
can show window preview for minimized windows in other places, like
Alt-Tab and Expose.
I removed this preference two years ago mechanically, by removing all
the if statements, but never went through and cleaned up the code so
that windows are simply mapped for the lifetime of the window -- the
"architecture" of the old code that maps and unmaps on show/hide was
still there.
Remove this now.
The one case we still need to be careful of is shaded windows, in which
we do still unmap the client window. Theoretically, we might want to
show previews of shaded windows in the overview and Alt-Tab, so we remove
the complex unmap tracking for this later.
This reverts commit ebe6e3180e.
This is wrong, as mutter's controlling TTY may not be the same
as the active VT, and in fact won't be in the case of systemd
spawning us.
The "correct" API for this is to use David Herrmann's
"Session Positions" system to switch to another VT:
http://lists.freedesktop.org/archives/systemd-devel/2013-December/014956.html
cogl_texture_get_format() has been deprecated, so rather than using
it to figure out beforehand whether the buffer format is supported,
just rely on the import failing if it isn't.
https://bugzilla.gnome.org/show_bug.cgi?id=722347
Under some circumstances, for example when the display controller driver
doesn't report back the correct EDID, or under VirtualBox, Mutter
returns suboptimal strings for an output display name, leading to funny
labels like 'Unknown 0"', or '(null) 0"' in the Settings panel.
This commit improves our heuristic in three ways:
- we now avoid putting inches in the display name if either dimension is
zero
- we use the vendor name in case we're not able to lookup its PnP id
from the database. Previously we would have passed over '(null)'
- as a special edge-case, when neither inches nor vendor are known, we
use the string 'Unknown Display'
Finally, we make the combined vendor + inches string translatable, as
different languages might want to move the size part of the string to a
position different than the end.
https://bugzilla.gnome.org/show_bug.cgi?id=721674
When GDK sends an unmaximize _NET_WM_STATE ClientMessage, it tells us to remove
the _NET_WM_STATE_MAXIMIZED_HORZ and _NET_WM_STATE_MAXIMIZED_VERT states. Before
this time, it would independently call:
meta_window_unmaximize (window, META_MAXIMIZE_HORIZONTAL);
meta_window_unmaximize (window, META_MAXIMIZE_VERTICAL);
Which, besides being foolishly inefficient, would also mess up our saved_rect
tracking, causing the window to only look like it was unmaximized vertically.
Make this code more intelligent, so it causes us to unmaximize in one call.
https://bugzilla.gnome.org/show_bug.cgi?id=722108
This grab was added in commit caf43a123fhttps://bugzilla.gnome.org/show_bug.cgi?id=381127
to minimize window flickering when switching workspaces.
While this grab is held, some signals are emitted to the shell,
which can lead to deadlocks (reproduced under Mali binary OpenGLESv2
drivers).
Now that we are a compositing window manager, we do not have to
worry about flickers, this grab should no longer be necessary.
https://bugzilla.gnome.org/show_bug.cgi?id=721709
Remove some obvious server grabs from the window creation codepath,
also ones that are taken at startup.
During startup, there is no need to grab: we install the event handlers
before querying for the already-existing windows, so there is no danger
that we will 'lose' some window. We might try to create a window twice
(if it comes back in the original query and then we get an event for it)
but the code is already protected against such conditions.
When windows are created later, we also do not need grabs, we just need
appropriate error checking as the window may be destroyed at any time
(or it may have already been destroyed).
The stack tracker is unaffected here - as it listens to CreateNotify and
DestroyNotify events and responds directly, the internal stack
representation will always be consistent even if the window goes away while
we are processing MapRequest or similar.
Now that there are no grabs we don't have to worry about explicitly calling
display_notify_window after grabs have been dropped. Fold that into
meta_window_new_shared().
https://bugzilla.gnome.org/show_bug.cgi?id=721345
The return code of XGetWindowAttributes() indicates whether an error
was encountered or not. There is no need to specifically check the error
trap.
The trap around XAddToSaveSet() was superfluous. We have a global error
trap to ignore any errors here, and there is no need to XSync() as GDK
will later ignore the error asynchronously if one is raised.
Also move common error exit path to an error label.
https://bugzilla.gnome.org/show_bug.cgi?id=721345
In meta_screen_manage_all_windows() we can use our own stack
tracker to get the list of windows - no need to query X again.
A copy is needed because the stack gets modified as part of the loop.
Specifically, meta_stack_tracker_get_stack() at this time returns the
predicted stack, and meta_window_new() performs a few operations
(e.g. framing) which cause immediate changes to the predicted stack.
https://bugzilla.gnome.org/show_bug.cgi?id=721345
meta_window_ensure_frame() creates its own grab and has a comment
claiming that it must be called under a grab too.
But the reasoning given in the comment does not seem relevant here.
We only frame non-override-redirect windows, so we are creating
the frame in response to MapRequest. There is no way that the child
could receive a MapNotify at this point, since that only happens
much later, once we go through the CALC_SHOWING queue and call
XMapWindow() from meta_window_show().
Remove the unnecessary grab.
https://bugzilla.gnome.org/show_bug.cgi?id=721345
Server grabs are not as evil as you might expect, but there is agreement
in that their usage should be limited.
Server grabs can cause things to go rather wrong when mutter emits
a signal while it has grabbed the server. If the receiver of that signal
waits for a synchronous action performed by another client, then you
have a deadlock. This happens with Mali binary GLESv2 drivers :(
https://bugzilla.gnome.org/show_bug.cgi?id=721345
The compositor code used to handle X windows that didn't have a
corresponding MetaWindow (see commit d538690b), which is why the
attribute query is separated.
As that doesn't happen any more, we can clean up. No functional changes.
Suggested by Owen Taylor.
https://bugzilla.gnome.org/show_bug.cgi?id=721345
As logind can give us a new FD at any time when it resumes. Theoretically,
this is still technically wrong, as the MetaCursorTracker holds onto it.
We'll fix this after we port to logind.
When we move focus elsewhere when unmanaging a window, we *need* to move
the focus, so if the target is globally active, move the focus to the
no-focus-window in anticipation that the focus will normally get moved
to the right window when the target window responds to WM_TAKE_FOCUS.
If the window doesn't respond to WM_TAKE_FOCUS, then focus will be left
on the no-focus-window, but there's no way to distinguish whether the
app will respond or not.
https://bugzilla.gnome.org/show_bug.cgi?id=711618
When a client spontaneously focuses their window, perhaps in response
to WM_TAKE_FOCUS we'll get a FocusOut/FocusIn pair with same serial.
Updating display->focus_serial in response to FocusOut then was causing
us to ignore FocusIn and think that the focus was not on any window.
We need to distinguish this spontaneous case from the case where we
set the focus ourselves - when we set the focus ourselves, we're careful
to combine the SetFocus with a property change so that we know definitively
what focus events we have already accounted for.
https://bugzilla.gnome.org/show_bug.cgi?id=720558
Initial placement during meta_window_constrain() can result in changes
to the borders, so we need to recompute our border sizes after
constraining. This fixes incorrect window borders on
initially maximized windows.
https://bugzilla.gnome.org/show_bug.cgi?id=720417
Currently the only way to move a window to another monitor via
keyboard is to start a move operation and move it manually using
arrow keys. We do have all the bits of a dedicated keybinding in
place already, so offer it as a more comfortable alternative.
https://bugzilla.gnome.org/show_bug.cgi?id=671054
Some drivers which support RandR 1.4 may not support setting
or getting the primary output, therefore mutter should trap
and ignore any relevant errors.
The modesetting driver exposes this problem when used in
combination with the nvidia binary driver using RandR 1.4
offloading.
Also use a local display variable instead of calling
meta_get_display () every time.
Do this by duplicating the current code and porting it to use
X again. A better approach would involve our own event structures,
and I really don't want to do that right now. We can clean this up
later.
The grab_window might be NULL, in which case we have a full-screen
grab, but we might still in a grab. Correct the check by asking
whether we're in a grab op or not.
When unmaximizing, we changed bits of window state, then called out
to code that used the frame extents *before* we cleared old cached
extents. Clear the cache up-front as soon as we change the window
state.
https://bugzilla.gnome.org/show_bug.cgi?id=714707
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
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.
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.
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
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
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
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
