minWidth and minHeight arguments of the Button class were not used.
Panel buttons need their height to be explicitly specified as
PANEL_HEIGHT to take up full panel height. This fixes the problem with the
user not being able to click at the very top edge of the panel to activate
the button.
This is a start at the "Active Appliction Item" component of the
shell design. Currently we just show the currently focused
application. When launching a new application, we show that as well.
The implementation here is not complete; basically when launching
we de-focus the active one, and the application well shows the
most recent startup sequence.
This kind of fails in the case of multiple sequences, and we
also don't correctly de-focus the current window in other
launch paths.
There was lots of fixed positioning in the Panel; now it is completely
dynamic, and width/height is driven from main.js. We still have a
global constant Panel.PANEL_HEIGHT, but this is a big step towards
eliminating it.
Also, this avoids overdraw in the "way too many tray icons" case. The
clock will shift left.
Replace 'overlay' with the more descriptive name 'overview'
where the Activities Overview is meant. Call it Overview
(capitalized) in code comments.
The overlay-group and overlay-key provided by Mutter are not
affected, since they may be used for other components than
the Activities Overview.
Instead of only transforming the active workspace, create a
zooming effect when showing or hiding the overlay. This makes
the transitions simpler: the workspaces are now fixed to the
overlay actor group and will not slide over the Dash.
overlay.js: Add zoom animations, fade in/out Dash during those,
remove obsolete Dash clipping and stacking logic, add public
get[Scale|Position]() and getZoomedIn[Scale|Position]()
functions.
workspaces.js: Remove zoom animations, add fade animations for
the remove button, add helper functions for the overlay
zooming, keep the movement of windows linear to that of
their workspaces, remove the updatePosition() and
updateInOverlay() functions and fullSize variables that
were left from the old overlay design.
The "expanded background" that is behind the workspaces etc. in the overview
should be removed. It isn't in the designs, it is distracting, and it breaks
the overview metaphor.
At least temporarily, just make the background of the overview black.
Change the pane popup to black as well, but keep a blue border so that
it is visually distinguished from the background.
Based on a patch by Colin Walters, with fixes from Marina Zhurakhinskaya.
It's both intuitive to go to the corner of the screen
and click the activities button at the same time.
Both actions bring up the overlay, but combined
they cancel each other out. This commit makes
clicking the hot corner not cancel the act of
going to the hot corner.
Based on a patch from Ray Strode.
The scale of windows within a workspace is determined by the
scale of the workspace since we never scale a window bigger
than the original size of the window. So when we rescale
workspaces we have to rerun Workspace.positionWindows().
http://bugzilla.gnome.org/show_bug.cgi?id=591124
The onComplete when positioning windows may come before the
final stage of the workspace positioning animation. So we can't
use actor.get_transformed_position() to figure out where to put
the icons. Compute the final position manually ourselves instead.
http://bugzilla.gnome.org/show_bug.cgi?id=591123
Both the position and size of the frame actor depend on the scale
of the workspace, so update them both when the scale changes.
On the other hand, the the frame actor doesn't need to be
repositioned when the workspace moves (since it is relative to the
workspace). We do base the frame position of the desktop actor, but
that will presumably stay fixed (at 0,0) in most all cases.
http://bugzilla.gnome.org/show_bug.cgi?id=591122
When Workspace._positionWindows is called, the clone might nto
yet have its final size (because of the clone is is a clone of
the window texture and the window texture isn't updated until
right before painting.) So get the size from the MetaWindow
instead ... the MetaWindow size is determined synchronously when
the window is managed.
http://bugzilla.gnome.org/show_bug.cgi?id=590741
Take everything in the ~/.gtk-bookmark lines after the URI
as label, not only the first word. (eg. if there's a line like
"file:///home/rainct/Ubuntu%20One Ubuntu One", now "Ubuntu One"
is taken as the label, instead of only "Ubuntu").
Pass the error variable to g_key_file_load_from_data_dirs in
Shell.AppSystem.get_default().load_from_desktop_file again, and
use a try/catch in places.js.
- Avoid error '"iconname" may be used uninitialized in this function'
by initializing said variable to NULL.
- Define shell_util_get_file_description as static (like the other
similar functions) to avoid another compiler error.
- Don't save errors from g_key_file_load_from_data_dirs into the
variable "error" (ie. pass NULL to it instead). Without this,
gnome-shell crashes if the key file can't be found (with message
"Error invoking Shell.load_from_desktop_file: Valid key file could
not be found in search dirs").
- Check the result of the load_from_desktop_file() call in places.js,
as it may be null.
Previously, ShellAppSystem only loaded (and cached) the set of
.desktop files from applications.menu and settings.menu, using
the gnome-menus library. The ShellAppInfo structure was
a "hidden typedef" for GMenuTreeEntry.
But we need to support loading an arbitrary .desktop file. Thus,
refactor the ShellAppInfo into a real struct, with a refcount,
and allow it to point to either a GMenuTreeEntry or a GKeyFile.
Also, in the case where we fail to lookup an icon for an
application, ensure we return a 0 opacity texture.
When WellGrid had no child it was doing a division by zero,
which screwed up the calculation for the height request and
having it ask for a negative number. This commit fixes this
by always requesting 0 in this case.
I've done some little modifications to the window positioning code
used in the overlay so that it considers the height of the windows
and they don't overlap or get out of the workspace.
I've also raised the hard-coded scales a bit to have the windows as
big as possible without overlapping (this could use some testing on
a non-widescreen monitor).
Use ShellGenericContainer to implement a fully dynamic layout
for the application well. It's still fixed to 4 columns by default,
but no longer requires a fixed width to be passed in on start.
With another chunk of work, it could likely try to adjust to
the case where we can only fit fewer than 4 items in the well.
Remove the border highlighting on mouseover, since that caused
reallocations, and the grid layout isn't trivial.
Delete the unused shell_global_get_word_with function.
The variables this._yOffset and this._xOffset are included in the
drop coordinates, but as far as I can tell never defined. Looking
back on the commit that introduced this code, they weren't removed
from anywhere else either.
The drop coordinates seem correct without them, so just delete them.
Use the 1x1 actor in the top left corner of the screen to enter and leave
the overview mode by just moving the mouse over to it.
No delay is used for triggering the hot corner because a delay significant
enough to allow moving away the mouse to avoid triggering it ruins the desired
flow when triggering the hot corner is actually intended.
The hot corner is not enabled in the full screen mode because the application
or the virtual system might have a hot corner of its own in that place.
It's easier to explicitly call Main.overlay.hide() instead
of chaining activation signals, this got lost in a mix between
the big dash rewrite and ongoing changes to the Application well.
To better distinguish between vast fields of white of which many
windows are composed, add the application icon to the bottom
right of the window.
We fade them in to avoid an abrupt feel. The icons are in the
workspaces group, not individual workspace groups to avoid
having to adjust them when we scale the workspaces.
Replace Workspace._lookupIndexAndClone with Workspace.lookupIndex,
and make the caller go from index to clone, or clone and index.
Emit the signal at the correct time to take action
on snapback (i.e. after the end of the snapback animation).
Add a boolean to the drag-end signal saying whether it was accepted,
which ensures consumers know whether the drag was successful.
Tweak arrangements with 2,3,4,5 windows in a desktop so:
- Windows are a bit bigger
- All windows for 5 windows are equally sized instead of making
the windows in the bottom row larger
This does cause some more problems with tall windows overlapping
or running off the edge of the workspace, but it's an overall
small improvement to the behavior.
Move the GStreamer initialization from the Javascript code into
shell_recorder_init(). This avoids a dependency on the GStreamer
introspection information and will make it easier to drop the
gir-repository module dependency.
Said function in genericDisplay.js was returning the index of the
actor based upon its position in the entire list, while everywhere
else indexes relative to the currently displayed page were used.
This made actions in the details pane break (bug #590949), so I
replace it with a new function in shell-overflow-list.c,
shell_overflow_list_get_actor_index, which is page based.
This patch is a near-total rewrite of the Dash. First, the dash
code moves into a separate file, dash.js.
Inside dash.js, the components are more broken up into separate
classes; in particular there's now a Pane class and a MoreLink
class. Instead of each section of the dash, when activated,
attempting to close all N-1 other sections, instead there
is the concept of a single "active pane", and when e.g. activating
the More link for documents, if we know there's an active pane
which happens to be the apps, close it.
Many redundant containers were removed from the dash, and all
manual width, height and x/y offsets are entirely gone. We move
the visual apperance closer to the design by using the view-more.svg,
etc.
To complete the removal of height/width calculations from the dash,
we also had to do the same for GenericDisplay. Also clean up
the positioning inside overlay.js so calculation of children's
positioning is inside a single function that flows from screen.width
and screen.height, so in the future we can stop passing the width
into the Dash constructor and call this once and work on screen
resizing.
The previous application monitoring code was originally designed
to be based on WM_CLASS, which was then resolved on a server.
We have that resolution code locally now, so instead
of saving WM_CLASS data, save application IDs.
Also, inside the WM we have a much better
infrastructure for tracking windows. In particular, rather
than polling, we can just watch for focus notification on
the display, and window add/remove.
Instead of polling XScreensaver, use DBus to watch org.gnome.Session
which already has an idle time watch.
Now there is no polling at all inside the monitor.
Add a Notebook class which we then use to pack in separate Hierarchy
and Properties tabs.
Split out the inspector into its own class to avoid bloat in the
main class.
5 seconds is should help ensure we lose work less often on
Alt-f2 restart.
Avoid saving empty lines to history, and filter them out if
we find them.
Minor fixes for the still-not-enabled inspector.
This patch attempts to adjust if we have many tray icons; currently
the simple algorithm is to drop down to a spacing of 8 if we have
more than 6. In the future we should fix the panel layout so that
the clock moves to the side.
Add a dropdown pane triggered by Alt-F2, "lg" which supports interactive
JavaScript evaluation, saving/restoring a history file, as well as
an inspector element to pick by using the mouse.
Using an internal boolean rather than the visibility property seems
more reliable to me. Add a list of internal functions rather than
an if/else chain, so for example an extension could hook something on.
Delete the javascript evaluator in favor of the upcoming lookingGlass.js.
We had duplicate code in appDisplay and workspaces for handling activating
a window; unify that inside workspaces, add an API to Main.overlay to
access it from both contexts.
Also, explicitly raise the clone we're activating to the top
before starting the animation to leave the overlay.
Two calls to _repositionDetails() were done too early,
before the visibility of the results pane had changed,
so they had no effect. Thus when a search was done while
a details pane was active, the pane with the results was
hidden by the details pane.
In addition to fixing this, move the two remaining calls to
the line after changing the results pane's visibility
to make it clearer why the calls are there.
Don't use a clone of an actor that's not part of the scene graph for the
item previews. This patch fixes previews in the details pane for documents
for which we don't have full previews and for applications.
Use create_icon_texture() from AppInfo instead of looking up the file
for gicon when creating an application icon for the details pane.
Now clicking on the information icon of the same item a second
time will hide the details pane. Clicking it another time will
show it again, etc.
This is achieved by adding a 'toggle-details' signal which
switches the visibility of the details pane.
Other than the necessary changes, function _selectIndex (in
genericDisplay.js) has been restructured a bit to avoid
duplicating checks.
The experiment with avoiding ellipsization was a definite failure;
several translations have very long names, and we'd end up
with a single column.
Also fix extra padding; we only want some space at the top, not
left/right.
Rename DocsWidget to RecentDocsWidget (as widgets for most used docs,
docs related to the currently open documents, etc. may be added in the
future), and change the title so that it doesn't abbreviate 'Docs' (for
consistency with the overlay).
Corresponding with the design, if an application is in a running
state (has > 0 windows open), draw a glow behind the name.
To make the display look a bit nicer, set the width of each item
to be equal to the longest word among all the items.
Make dash background darker so that the blue color used for indicating
running apps can be visible. Use the dark blue (almost black) color from
Jeremy's mockup.
Make the dash height be the full screen height minus the height of the panel.
Don't use padding on top or on the bottom.
Remove the border from the main dash, but leave it for the results and details
panes. Make the border slightly transparent.
Make sure the details pane is correctly positioned by not applying the
additional padding when determining its x position.
Timeout callback function should not be rescheduled again with the same timeout
because we compute a new timeout and schedule it again instead. So the callback
function needs to return false to not be scheduled again by default.
Make sure that we calculate the next update time correctly.
Store timeout time instead of the timeout delta, so that it doesn't get outdated.
Create a new callback when the time update happens for the original callback.
Make sure last visited time is updated in the details pane by keeping track
of the description actors created for the detail actors.
Add comments to the new functions.
Extend ShellTextureCache by adding the concept of a policy, which
we expose to the public API for loading URIs.
This lets us have the shell tell the cache to keep the information
icon texture around forever.
Secondly, fix the caching of recent info; we shouldn't always be
loading the backup pixbuf. Move recent info loading entirely
into ShellTextureCache.
The semi-transparent gradient on the panel is replaced by a
solid black background. The shadow below the panel is removed.
The clock is put at the center instead of the right side of
the panel and has the date removed. The user icon is hidden.
Instead of boldface, a regular font is used. Padding is added
on each side and between panel elements.
button.js: Allow for custom text colors and fonts.
panel.js: Change the panel colors and layout, remove the shadow.
GenericDisplay wasn't quite completely converted to the ShellOverflowList
model. Since the list now holds all actors, the indexing/wrapping
was incorrect.
Add a property which lets us keep track of how many items are displayed,
use this in genericDisplay.
Avoid setting selectedIndex to -2 when going up with no items.
If we're not displaying any results at all, don't attempt keynav (for now).
Make the ClutterText and ClutterTexture from the status menu
button available to JavaScript, and from there improve the
font definition of the user name.
shell-status-menu.[ch]: Add public get_name() and get_icon()
functions that return the user name label and icon
texture, remove the markup from update_name_text().
panel.js: Set the font for the button consistently with that
of the other panel labels.
Move thumbnail creation into ShellTextureCache. It's now asynchronous,
and we cache the result.
Create a DocManager class which keeps around the DocInfo objects between
invocations. This is also where we ensure we remove thumbnails for
recent items not known anymore.
Before, we looked up application data in several ways; the ShellAppSystem
exported just application ids (though it parsed the .desktop files internally),
and we'd create a Gio.DesktopAppInfo object (reparsing the desktop file again),
wrapping that inside a JavaScript AppInfo class, and finally the AppDisplay
would again parse the .desktop file to get the categories.
Also, to look up applications by id previously, we traversed the entire
menu structure each time.
Some qualities such as the NoDisplay flag were not easily exposed in the old
system. And if we wanted to expose them we'd have to change several different
application information wrapper classes.
All in all, it was quite suboptimal.
The theme of this new code is basically "just use libgnome-menus". We do
not call into Gio for app lookups anymore. The new Shell.AppInfo class
is a disguised pointer for the GMenuTreeEntry item.
To fix the caching, we keep a simple hash table of desktop id -> ShellAppInfo.
Rework the previously extant Application category code to display
in the expanded list. Add a "Frequent" category which corresponds
to the most_used_apps, and selected by default.
Instead of adding the background and shadow as expanded items to
the results/details panes as fixed, we slave the background/shadow
sizes to the results using notify::allocation.
Also clean up the code for sizing the details pane, using a common
function which adjusts its x position in one place.
The split between this.actor and this.nonOverlayActor in chrome.js is
annoying, but aside from actually subclassing ClutterGroup (which
would have to be done from C), all of the other possibilities are
annoying too.
Add a new icon button in button.js that fades in/out with a short delay when the mouse enters/leaves its parent. Use it for the information button of genericDisplay.
This converts GenericDisplay to totally dynamic layout, where
we display as many items as we can, and the rest cleanly overflow
into pages.
For now, remove multi-column; to readd this, we can pack multiple
display items into a single ShellOverflowList item.
It looks funny to have the "more running apps area" there as a gap
when empty and dragging to it is an unintuitive way to remove stuff
from the favorites list, in any case, so just hide the area when
empty.
http://bugzilla.gnome.org/show_bug.cgi?id=587720
Pack everything we don't want to expand with BigBoxPackFlags.NONE;
this fixes the More... button for the docs section ending up with
a gap underneath it.
Since the More... button for the docs now ends is right at the bottom
of the dash, add some padding to it.
http://bugzilla.gnome.org/show_bug.cgi?id=587720
Widgets should be horizontally centered in the sidebar. Else they look
out of place (in particular the clock and the applications widgets).
Due to little tricks with the sidebar starting out of the screen to
hide rounded corners, this implies playing with paddings. The patch
decreases the widgets padding from 4 to 2 pixels, removes additionnal
padding on the right, and adds an out-of-screen padding to the widget
box to make up for the negative horizontal position of the sidebar.
The width of a Group actor ends up including the width of its hidden children,
so we were getting a reactive object as wide as the details pane that was
blocking the clicks to the workspaces underneath it even when the details
pane was actually hidden.
Not making the dash Group actor reactive solves this problem. However, we
have to make individual parts of the dash reactive instead so that the clicks
are not passed to the transparent actor underneath them. That transparent
actor is used for dismissing the additional panes when the user clicks over
the workspaces area.
Clutter no longer allows using a clone of an actor that is not a part of
the scene graph. This is what used to happen when we created a clone for
the icon of the item that was being dragged, and then closed the More panes
with the original item, removing the icon from the scene graph. This was
also when happened when the user hit Esc while dragging, which prompted the
overlay to close, removing the original icon from the scene graph.
Rename getIcon() methods to createIcon() to better reflect on the fact that
a new icon is created each time the method is called (we do use cache in
some cases).
Remove a stray log message in overlay.js
Fixes http://bugzilla.gnome.org/show_bug.cgi?id=585490
and http://bugzilla.gnome.org/show_bug.cgi?id=585489
The new class AppWell implements the application favorite well
in the Dash component. The previous AppDisplay remains for use
in the More... mode now.
Delete DEFAULT_APPLICATIONS; this is now in GConf.
Rename getMostUsedApps to getTopApps since we now have the
idea of explicit favorites.
Delete some GenericDisplay-related calls from overlay related
to the seletion - we'll reimplement keyboard nav in a more
coherent way later.
AppResults and DocResults classes were identical with an exception of
the display class they used and the text label for the results. Merged
them into a single ItemResults class that takes these two additional
arguments.
Move the activate and select functionality inside the callbacks for
'button-release-event' signals of the display item and the information
button correspondingly. This way it is more obvious that this is an
event handling code that needs to return a boolean value for whether
the signal has been fully handled by the actor.
Update the code for checking a display item under the pointer to expect
the item itself rather than its child to be returned by stage_get_actor_at_pos().
This code is now used to display an information button when an item is
drawn under the pointer, so update the comment accordingly.
Add a comment about the use of the transparent background to catch clicks
in the workspaces area when the dash panes are being displayed and dismiss
the dash panes.
Set opacity for the background to 0 instead of using a transparent background
color so that Clutter optimizes the drawing of the background actor.
Fix up the comments about the horizontal gradient code and use 8x1 texture
instead of 8x8.
Make sure the values we assign to the three-stop horizontal gradient
require the use of the three stop gradient, with the middle value not being
right between the side values.
Display a pane with search results for both applications and documents
automatically when a search string is entered.
Allow viewing search results for the individual section when More link
for applications or documents is clicked.
Move text labels for the applications and documents sections into the
respective classes.
Enable typing in the search box and display results in the results pane.
This means that the user has to open the details pane for applications
or documents to view the results for now.
Connect Enter to launch the seleted item.
Connect Escape to clear search, remove results and details panes,
or exit overlay.
The results sections no longer include a label on top of them, so the
height of that label needs to be subtracted when specifying the height
for the sections. This ensures that display controls are positioned
correctly on the bottom of the section.
Clicking the information button for an item selects it (i.e. highlights it)
and shows details about the item.
Clicking the rest of the item area launches it.
Item does not become draggable if the dragging is started over the information
icon (i.e. if the user presses the information icon, but releases elsewhere).
Make sure we emit "activated" signal and close the overlay when an item from
one of the results displays is launched.
Use an (i) icon supplied by Jeremy for the information link and display
it on hover. Make sure it is positioned nicely and the text doesn't
overlap with it.
Pop-up previews are not part of the new design and interfere with the information link.
Make sure details display for applications has the appropriate width set.
Make sure at most one item is selected in the overlay and we always show
a details pane for the selected item.
Improve the positioning of the search box.
Remove a duplicate variable DASH_PAD and use DASH_SECTION_PADDING everywhere instead.
A blue selected item color fits better with the new color scheme than a green one.
Only one item should be selected across all the displays we are showing.
Display a pane with item details, such as a full image previews, when an item is single clicked.
Add a placeholder information link that shows up when an item is moused over.
Display all recent documents in the results pane, in addition to the first
few displayed in the main dash. All documents can be viewed with the help
of a paging control.
Display the results pane above the workspaces. The results pane is somewhat
transparent and has a blue gradient background. The dash pane is slightly
transparent and also has a blue gradient background.
The results pane shows up when a More control is clicked. It disappears when
a Less control is clicked, an area outside of the dash area is clicked,
an item starts being dragged, or the overlay mode is exited.
Add shell_global_create_horizontal_gradient() to shell-global.[ch]
Increase the priority of the idle for updating work area and struts
to META_PRIORITY_BEFORE_REDRAW. This prevents it from being starved
by a constantly-redrawing client.
http://bugzilla.gnome.org/show_bug.cgi?id=585500
The list of all applications was based on the items that show up in
the menus, and might not have contained all applications returned
by the AppMonitor for the most used applications request. One example of
such an application was Evince. This resulted in a crash when an
application we did not prepare the info for was returned as one of the
matches by the AppMonitor, so we now include all applications returned
by the AppMonitor in the list, in addition to the ones from the menus.
Also mark apps as stale when we catch a "changed" signal from the AppMonitor
to ensure that the cache is refreshed.
With commit a3d35af444 variable
itemInfo in js/ui/appDisplay.js was changed to a new object
(AppInfo from js/misc/appInfo.js) but some of the code in
js/ui/appDisplay.js wasn't updated accordingly. This commit
fixes that and makes the search box in the overlay usable
again.
This lets us share the recent-app-tracking, recent-file-tracking, and
icon-drawing code between the overlay and the sidebar, without the
sidebar having to poke into AppDisplayItem and DocDisplayItem's guts.
Currently function shell_get_thumbnail_for_recent_info located in
src/shell-global.c is used to get thumbnails for recently used files.
However, it only works if you have a GtkRecentInfo object for the file,
even though the thumbnail generation code doesn't depend on it. This commit
renames the function to shell_get_thumbnail and makes it generic so that it
just takes two strings: a filename and a mimetype.
- clutter_actor_get_transformed_position()/size() return floats
- clutter_stage_get_actor_at_pos() takes a pick mode
- ClutterTimeline no longer has a concept of frames
- ClutterUnit is now replaced by float
- cogl_texture_new_from_data() signature changed
http://bugzilla.gnome.org/show_bug.cgi?id=585013
This removes the border and padding and aligns the box to the top. Perhaps we
could push the padding down into the active area of the icon since it does look
a bit nicer with it.
http://bugzilla.gnome.org/show_bug.cgi?id=583139
The animation time for the overlay is a bit long. We're using 0.5 second.
From my quick tests of "another system" it takes about half that time to
animate. The other system feels about right.
http://bugzilla.gnome.org/show_bug.cgi?id=583572
The code here is significantly cleaner if we use the data Metacity
already has cached and validated, rather than talking to X directly.
Also some preparatory work for extending the monitor API by
clarifying the name of the (current) main entry point.
Change the "overlay" actor to be a group of 4 actors that we can
rearrange so as to have a hole in the middle (to cover up the whole
screen except for the highlighted icon). For non-iconified windows, we
still highlight them the old way (raising them above the overlay),
because we don't want square highlights around shaped windows.
Make the indicator in the pop-up move faster.
Quickly fade in the "overlay" window when starting, rather than
showing it abruptly. Destroy it right away rather than just hiding it
when the AltTabHandler is destroyed.
Fix the font size to be the same as the "Activities" button.
Fix a warning when tabbing past an iconified window.
To avoid loading applications from two different systems, use
ShellAppSystem solely. This unifies the initial load and the
reload.
Extend ShellAppSystem to also load settings/preferences, and
ensure they appear in the search.
Drag and drop was not working since the (non-reactive, invisible)
chrome group was on top of most of the screen. Explicitly set
a 0x0 size on that group to resolve the problem.
The goal of the workspace view is to identify and select windows. Transparency
results in the blending of the window and the background (and icons on the
desktop). I think the transparency is counterproductive.
We used it in the initial mockups kind of as a lark - it wasn't well thought
out.
http://bugzilla.gnome.org/show_bug.cgi?id=582647
Add a ShellTextureCache class which loads (and can cache)
pixmap->texture conversions. This fixes a problem with the
async code in ClutterTexture that it was lower priority
than animations, and also ensures we're really only
loading these pixbufs once in the icon case.
Adds an explicit "chrome" layer for the panel (and later the sidebar),
managing the input region and struts for them, and hiding them when
fullscreen windows are present or the user enters the overlay.
http://bugzilla.gnome.org/show_bug.cgi?id=581771
