At the point it is disabled, it has got signal handlers connected but
this._workspacesView is uninitialized. This triggers:
(gnome-shell:3993): Gjs-WARNING **: 18:49:53.281: JS ERROR: Exception in callback for signal: cancel: TypeError: this._workspacesViews is undefined
_endTouchGesture@resource:///org/gnome/shell/ui/workspacesView.js:527:25
_emit@resource:///org/gnome/gjs/modules/signals.js:142:27
set enabled@resource:///org/gnome/shell/ui/windowManager.js:478:13
WorkspacesDisplay<@resource:///org/gnome/shell/ui/workspacesView.js:482:9
ViewSelector<@resource:///org/gnome/shell/ui/viewSelector.js:167:35
ControlsManager<@resource:///org/gnome/shell/ui/overviewControls.js:405:29
init@resource:///org/gnome/shell/ui/overview.js:234:26
_initializeUI@resource:///org/gnome/shell/ui/main.js:184:5
start@resource:///org/gnome/shell/ui/main.js:124:5
@<main>:1:31
On startup. Shuffling these two lines prevent this from happening.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/506
Now that the existing touch/touchpad gestures in windowManager only
handle normal mode, add corresponding gestures for the overview and
hook them up to the existing workspace scroll animations.
https://gitlab.gnome.org/GNOME/gnome-shell/issues/516
ES6 finally adds standard class syntax to the language, so we can
replace our custom Lang.Class framework with the new syntax. Any
classes that inherit from GObject will need special treatment,
so limit the port to regular javascript classes for now.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/361
This attribute was previously only assigned in show(). hide() compares
this attribute to 0. If hide() is called before show() is first called,
the comparison would give the correct result (undefined > 0 is false)
but log a warning:
JS WARNING: [resource:///org/gnome/shell/ui/workspacesView.js 529]:
reference to undefined property "_restackedNotifyId"
Initialize this attribute in _init(), alongside _scrollEventId and
_keyPressEventId which are also used in hide().
Remove any usage of MetaScreen, as it has been removed from libmutter
in the API version 3. The corresponding functionality has been moved
into three different places: MetaDisplay, MetaX11Display (for X11
specific functionality) and MetaWorkspaceManager.
https://bugzilla.gnome.org/show_bug.cgi?id=759538
When not using arrow notation with anonymous functions, we use Lang.bind()
to bind `this` to named callbacks. However since ES5, this functionality
is already provided by Function.prototype.bind() - in fact, Lang.bind()
itself uses it when no extra arguments are specified. Just use the built-in
function directly where possible, and use arrow notation in the few places
where we pass additional arguments.
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/23
Any symbols (including class properties) that should be visible
outside the module it's defined in need to be defined as global.
For now gjs still allows the access for 'const', but get rid of
the warnings spill now by changing it.
https://bugzilla.gnome.org/show_bug.cgi?id=785084
It is odd to switch workspaces on the primary monitor when panning on
a monitor without workspaces, so reject the gesture on non-primary
monitors when workspaces-only-on-primary is disabled.
https://bugzilla.gnome.org/show_bug.cgi?id=766883
It is odd to switch workspaces using the scroll wheel when the pointer
is on a monitor without workspaces, so only handle scroll events on
non-primary monitors when workspaces-only-on-primary is disabled.
https://bugzilla.gnome.org/show_bug.cgi?id=766883
We allow activating a workspace by clicking it when we know that
the user did not try to select a window and missed (namely: the
workspace is empty). However we currently always check for an
empty workspace on the primary monitor, which doesn't make sense
when the click happened on a different monitor.
https://bugzilla.gnome.org/show_bug.cgi?id=766883
Initializing the upper bound to zero means that on panning we'd start
scrolling from the first workspace even if the current workspace when
entering the overview was different since StAdjustment clamps the
value to be inside bounds.
https://bugzilla.gnome.org/show_bug.cgi?id=766883
This works for pointers and touch on X11, there is however no pointer
emulation on evdev, so touch triggers ::clicked with button==0 which
is ignored.
https://bugzilla.gnome.org/show_bug.cgi?id=756748
To switch workspace by keyboard in the overview, the user currently
has to use the normal keybinding. However as the vertical alignment
of workspaces makes them very similar to pages in the app picker, it
makes sense to also support the standard pageUp/pageDown keys.
https://bugzilla.gnome.org/show_bug.cgi?id=742581
It is quite weird to have those calls/signals using WindowClone as an
argument, it is neater to pass MetaWindows around, and have each user
deal with their own representations of these.
https://bugzilla.gnome.org/show_bug.cgi?id=735972
And use it to lookup the local WindowClone that applies. Otherwise,
WorkspaceThumbnail.WindowClone objects may be mistakenly set, which
are not usable interchangeably with Workspace.WindowClone ones. This
may lead to several misbehaviors as fields available in the second
object but not in the first one are accessed, some those undefined
values get used in math ops, which result in NaNs over the place.
Likewise, the similar functions in WorkspacesViewBase subclasses take
now MetaWindow arguments too.
https://bugzilla.gnome.org/show_bug.cgi?id=735972
The zooming animation of the windows looks nice when animating
from the workspace display page, but looks weird from other pages
like apps page or search page since the windows come from nowhere
with an initial position not known to the user.
Instead of that just fade the desktop with the windows in its
original position.
https://bugzilla.gnome.org/show_bug.cgi?id=732901
They are different properties, they deserve different syncs.
Especially because a full allocation cycle sets both anyway, so
we should save some cycles this way.
https://bugzilla.gnome.org/show_bug.cgi?id=729823
By default, gesture actions no longer wait for the dnd threshold to
be reached before triggering, which breaks our mixing of click- and
pan actions. Fix this by only panning after reaching the threshold
and letting the click action go through if the pan is cancelled.
https://bugzilla.gnome.org/show_bug.cgi?id=722417
Workspaces can removed from any index, and in particular they
will be removed by the WorkspaceTracker if they stop containing
windows at some point. Make sure WorkspacesView is not confused
and destroyes the right Workspace objects.
https://bugzilla.gnome.org/show_bug.cgi?id=721417
Simply use St's existing key navigation system by making all the window
clones StWidgets, and making the WorkspacesView a focus group.
Since the workspace view is effectively "fake", we need to add a focus
delegator so that when key focus is assigned to the fake workspaces page,
we can keynav inside it properly.
https://bugzilla.gnome.org/show_bug.cgi?id=644306
Before, workspacesOnlyOnPrimary was implemented in quite a crazy manner:
* If workspacesOnlyOnPrimary was false, we'd create one WorkspacesView per
monitor, with the primary one being a bit special.
* If workspacesOnlyOnPrimary was true, we'd create one WorkspacesView, and
additional montiors would be handled inside that WorkspacesView as
"extra workspaces".
This caused numerous bugs as the two modes weren't consistently
implemented, and a lot of code was duplicated between all the modes.
Fix this by always creating WorkspaceViews, even if it only handles
one interface. We do this by having two different WorkspacesView-ish
classes: WorkspacesView handles the traditional combination of lots
of workspces, and a new ExtraWorkspaceView is in control of only one
workspace.
Right now, the workspace update code is complex and spread across parts:
WorkspacesView takes a set of workspaces and looks like it owns them, but
WorkspacesDisplay is actually in charge of setting them up and creating
new ones for each WorkspacesView.
Change initialization and handling to move all of the creation/destruction
responsibilities to WorkspacesView.
We pass in monitorIndex into each WorkspacesView, which is a lie in the
workspacesOnlyOnPrimary case, as the primary WorkspacesView currently has
the responsibility of handling the extra workspaces on all the other
monitors. The commit will clean this up and punt the responsibility back
to WorkspacesDisplay.
Commit 16fa186b63 attempted to fix the zoom animation problem
by throwing changes on the floor while the overview is animating. This has
the side effect that we might end up missing some positioning changes causes
windows to overlap the workspace thumbnails.
So revert those changes and fix it by simply by passing
WindowPositionFlags.ANIMATE during the overview animation.
This way the animation works as expected and we don't miss any position changes.
https://bugzilla.gnome.org/show_bug.cgi?id=703105
When the allocation of the workspacesView changes during the animation we override
the tween with one that does not animate causing the overview zoom animation
not to happen.
Fix that by ignoring the alloactionChanged notification during the overview
animation.
If we created a workspace after showing the view, we would never
set the geometry on it, which would cause an exception in the
window layout code and leave the DND state tracking in an undefined
state.
https://bugzilla.gnome.org/show_bug.cgi?id=699029
Instead of doing an entire recalculation of window positions when
sliding the thumbnails box, simply recalculate the position and scale
with basic aspect ratio math. This also ensures that windows won't
miraculously swap positions, even if we reposition windows while the
thumbnails box is expanded.
https://bugzilla.gnome.org/show_bug.cgi?id=694469
As we want to eventually track two geometries, we need to rename
our very plain "_x, _y, _width, _height". While we could just prefix
them, I think that stuffing them in an object makes more sense.
At the same time, make the variable and method name more descriptive
by adding such a prefix, as well as a bit of documentation.
https://bugzilla.gnome.org/show_bug.cgi?id=694469
To ensure that we don't recalculate window layouts when zooming
in or out, we need to always pass the full geometry. This will
break window repositioning when we zoom back in; for the purposes
of commit clarity, this breaks this feature for now. It will be
added back soon.
https://bugzilla.gnome.org/show_bug.cgi?id=694469
DND of windows has a lot of side effects, including the possibility of
current workspace disappering from under our feet. We need to account
for that when trying to activate it.
https://bugzilla.gnome.org/show_bug.cgi?id=685285
When a swipe scroll completes, we scroll the active workspace into
view. This works fine if the gesture is completed properly by
emitting 'gesture-end', but not when Clutter considers the gesture
cancelled - in that case, the view remains stuck in an intermediate
position. To fix, treat 'gesture-cancel' the same as 'gesture-end'.
https://bugzilla.gnome.org/show_bug.cgi?id=689394
Both WorkspacesDisplay and ThumbnailsBox need to know when windows have been
restacked. Instead of each tracking changes on their own or trying to call
each other, have the overview keep track and do the calculations, emitting
a signal with the result.
https://bugzilla.gnome.org/show_bug.cgi?id=690175
The thumbnail controls are not a separate actor in the overview group
yet, so we need to ensure a spacing between them and the workspaces
view.
Instead of exporting the overview spacing, just add a temporary style
class to the workspaces-view actor for it. It will be removed in the
future when we change the layout of overview elements.
https://bugzilla.gnome.org/show_bug.cgi?id=690174
On additional monitors the workspacesView takes up the entire monitor
and in some cases windows in overview can end up hard against the
edge of the monitor.
https://bugzilla.gnome.org/show_bug.cgi?id=688133
Ouch. This went unnoticed for a long time as by default (using
dynamic workspaces) only one workspace is added at a time, which
happens to work fine.
https://bugzilla.gnome.org/show_bug.cgi?id=686487
Hide workspace switcher if dynamic workspaces is disabled and number of
workspaces is set to one only, since the user is bound to only one workspace
and showing the switcher is redundant.
Signed-off-by: Seif Lotfy <seif@lotfy.com>
Currently we animate scrolling to the active workspace both when
the number of workspaces changed and after changing the active
workspace. So in case we don't actually change workspace, this
results in an unnecessary animation that may even have unwanted
side effects: when done during the overview transition (e.g. in
the case of opening and activating a window on an empty workspace),
non-active workspaces become visible during the transition.
To fix, don't scroll to the active workspace when the number of
workspaces changes and rely on the 'switch-workspace' signal being
emitted as necessary.
https://bugzilla.gnome.org/show_bug.cgi?id=682002
Most of code implementing workspace switches was repeated with
minor differences on each direction. Instead, consolidate it
and use the new meta_workspace_get_neighbor.
https://bugzilla.gnome.org/show_bug.cgi?id=674104
Currently we only connect to the 'notify::n-workspaces' signal the
first time the overview is shown, which means we will miss any
changes to the workspace layout in the meanwhile.
In particular, the decision of whether the workspace switcher should be
shown is taken before the dynamic workspace handling takes over, and is
thus based entirely on the value of the num-workspaces user preference
rather than the actual number of workspaces.
Just connect the signal in _init() (with the nice side-effect to make it
explicit that the signal handler won't ever be disconnected).
https://bugzilla.gnome.org/show_bug.cgi?id=673198
We seem to have a lot of code that does something along the lines of:
if (condition)
actor.show();
else
actor.hide();
ClutterActor already has such a thing for exactly this purpose: the 'visible'
property. Use it instead of the mess above.
https://bugzilla.gnome.org/show_bug.cgi?id=672272
If the user has their mouse over the workspace thumbnails while
entering the overview, it's more likely that it's a coincidence
that their mouse pointer is in the area. Avoid expanding the
thumbnails box in that case.
https://bugzilla.gnome.org/show_bug.cgi?id=651092
When in overview, window labels flicker or are temporarily hidden on a
number of occasions - when simply clicking around the area the windows
are displayed in, dragging a window, sliding in the workspace list,
adding new workspaces etc. This patch makes the label for any window
visible at any given moment when in overview and the said window is
not being dragged around.
https://bugzilla.gnome.org/show_bug.cgi?id=644861
If workspaces-only-on-primary is false, swipe scrolling is now
broken with multiple monitors. To fix, let workspacesDisplay
handle swipe scrolling for all views.
https://bugzilla.gnome.org/show_bug.cgi?id=652580
If workspaces-only-on-primary is false, workspaces should be shown
on each monitor; rather than letting the existing workspaces span
the entire screen, manage one workspacesView per monitor (similar
to the extra workspaces in WorkspacesView when the setting is true).
https://bugzilla.gnome.org/show_bug.cgi?id=652580
Extra workspaces are special, in that they collect windows from
all workspaces for a particular monitor. This matches the default
behavior, but we need more than a single workspace per monitor if
workspaces-only-on-primary is false, so don't create the extra
workspaces in that case.
https://bugzilla.gnome.org/show_bug.cgi?id=652580
WorkspacesDisplay was introduced to manage the workspace objects
and views; however, the overview still accesses the view held
by the workspacesDisplay directly, which is a bit odd.
Add some additional methods needed by the overview, and make the
view a private property.
https://bugzilla.gnome.org/show_bug.cgi?id=652580
The last patch in the sequence. Every place that was previously
setting prototype has been ported to Lang.Class, to make code more
concise and allow for better toString().
https://bugzilla.gnome.org/show_bug.cgi?id=664436
js2-mode is no longer developed and we recommend js-mode these days,
so switch the modelines to specify that, and make them consistent
across all files.
https://bugzilla.gnome.org/show_bug.cgi?id=660358
When workspace "previews" in the overview were just tiny gray
rectangles, it made sense to provide a way to move windows
directly between workspaces (by switching workspaces when dragging
a window to the corresponding screen edge). As the overview has
evolved however, the workspace switcher provides a good and
intuitive drop target already, so the alternative provided by the
screen edges is no longer necessary. As it also conflicts with
moving windows between monitors when using a vertical layout,
just remove it.
https://bugzilla.gnome.org/show_bug.cgi?id=660838
Remove ShellGlobal's monitor-related methods, and have
Main.layoutManager provide that information instead. Move
Main._relayout() to LayoutManager, and have other objects connect to
the layout manager's 'monitors-changed' signal to know when the screen
geometry has changed.
https://bugzilla.gnome.org/show_bug.cgi?id=636963
Sliding out the workspaces pager when starting a drag causes a lot
of motion. With the pager only hiding if workspaces are not used,
it is better to require to explicitly hover the workspaces sidebar
for the sliding.
https://bugzilla.gnome.org/show_bug.cgi?id=652730
After completing the overview transition, the workspace view is
clipped to avoid overlapping the search entry/view selector titles
while switching workspaces. For clipping, the view's position and
size was used, which works well assuming that the workspace pager
will start hidden or stay zoomed out while the overview is visible.
However, that assumption holds no longer true, as auto-hiding the
pager now depends on the number of workspaces, and thus may change
while in the overview. For instance, when starting with the pager
being visible, the clip area ends up being too small when moving
all windows to the first workspace (and thus triggering auto-hide).
As a fix, handle the clip rectangle separately from the view's
geometry, and set it always to the area the workspaces would
occupy with the pager hidden.
https://bugzilla.gnome.org/show_bug.cgi?id=653142
With commit 59a3e393f9 whether the workspace pager should autohide
now depends on the number of workspaces. As we only track changes
to the number of workspaces while the overview is visible, we miss
changes in "normal mode", i.e. when creating a new workspace by
moving a window with ctrl-alt-shift-arrow; as a result, the pager's
autohiding might be incorrect when entering the overview after that.
As a fix, keep tracking changes to the workspaces when the overview
is hidden and update the zoom options.
https://bugzilla.gnome.org/show_bug.cgi?id=653078
The purpose of autohiding the workspace pager on the right was to
avoid exposure of workspaces to users who are not using them.
However, for users who do use workspaces, the behavior limits the
purpose of the overview. To fix, always show the pager if more than
one workspace is actively used.
https://bugzilla.gnome.org/show_bug.cgi?id=652714
Currently the user has to find an empty spot in the workspace
to be able to launcha new instance of an app using dnd.
This is unnecessary hard, so just allow dropping on windows too.
https://bugzilla.gnome.org/show_bug.cgi?id=652079
Currently the workspace geometry is updated on zoom/allocation
changes, which means that newly added workspaces use their initial
geometry of (0, 0, 0, 0) until the next zoom change. As a result,
windows on the affected workspaces are mispositioned, e.g. placed
outside the workspace area. To fix, set the geometry on newly added
workspaces to the view's cached values.
https://bugzilla.gnome.org/show_bug.cgi?id=649001
Workspaces used to contain the desktop background, so when a
workspace was removed, we animated its actor to an off-screen
position before destroying it. As the background has been
removed a while ago, we can destroy the actor directly.
https://bugzilla.gnome.org/show_bug.cgi?id=645031
We used used to indicate to the user the ability to move to another workspace
during dnd by highligthing the adjacent workspaces on hover.
This was done by changing the workspace's opacity to 200 and set it to
255 for the highlighted adjacent ones.
This is now no longer needed as the design was completely changed since
then (overview relayout; we no longer represent workspaces in the way
we did before) and introduces a bug where we don't properly reset the
opacity after the drag action, so just remove that code.
https://bugzilla.gnome.org/show_bug.cgi?id=648983
We need to update WorkspacesView._ZoomOut before calling
_updateWorkspacesGeometry() in show(), as otherwise the old
value is kept. This was a problem if we previously left the
overview zoomed out.
Currently activating a window on a different workspace requires very
long drag distances, which is very inconvenient to use.
Fix that by allowing switching workspaces using the thumbnails which is
consistent with window and launcher dnd and much easier to use.
https://bugzilla.gnome.org/show_bug.cgi?id=643945
If there is a monitor to the right it is very easy to overshot the
expanding thumbnails and enter the next monitor. So, in that case
we just always show it.
https://bugzilla.gnome.org/show_bug.cgi?id=641877
When we were knocking off workspace height to fix the ratio problems, we
weren't adding spacing in between workspaces, so they smooshed up against
each other whenever we took height off, causing them to be visible.
We clip the entire WorkspacesDisplay to its allocation to avoid things
like the WorkspaceThumbnails sticking out of the primary monitor into
another monitor.
https://bugzilla.gnome.org/show_bug.cgi?id=609258
We used to do this only on automatic workspace switch, but that
doesn't work for the multiple monitors case where we want to reserve
space on the extra monitors.
https://bugzilla.gnome.org/show_bug.cgi?id=609258
We create a Workspace with a null metaWorkspace for each
non-primary monitor, showing the windows on these monitors.
These are saved in WorkspaceView.extraWorkspaces.
https://bugzilla.gnome.org/show_bug.cgi?id=609258
This means a bunch of windows will not be visible at all in the overview.
Those will be added back with per-screen workspaces on the non-primary
monitors.
https://bugzilla.gnome.org/show_bug.cgi?id=609258
Commit 0207f1f29b landed a new
way of zooming, but was causing all sorts of window positioning
weirdness because the positions were supposed to be working against
a proportional workspace.
https://bugzilla.gnome.org/show_bug.cgi?id=644542
WorkspacesDisplay removes its dragMonitor in _dragEnd, but
this was never called in when a xdnd drag ended causing
dragMonitors to stack up and handling events multiple times.
Fix that by making sure that _dragEnd is called when xdnd ends.
https://bugzilla.gnome.org/show_bug.cgi?id=644642
We currently show the workspace in the overview in a rectangle
with the same aspect ratio as the screen. Originally this was
probably done since it showed the desktop, but we don't do this
anymore, and the positioning of the windows in the overview is
strictly a grid, so its not in any way related to monitor geometry.
Additionally, in the multihead case the screen aspect ratio is
very different from the overview monitor geometry, so a lot of
space is lost.
So, instead we just fill the entire inner rectangle of the overview
with the workspace. However, the way the zoom into and out of the
workspace right now is by scaling the workspace so that it covers
the entire monitor. This cannot really work anymore when the workspace
is a different aspect ratio. Furthermore the coordinates of the
window clone actors are of two very different types in the "original
window" case and the "window in a slot case". One is screen relative,
the other is workspace relative. This makes it very hard to compute
the cost of window motion distance in computeWindowMotion.
In order to handle this we change the way workspace actor positioning
and scaling work. All workspace window clone actors are stored in
true screen coordingates, both the original window positions and the
in-a-slot ones. Global scaling of the workspace is never done, we
just reposition everything in both the initial zoom and when the
controls appear from the side.
There is one issue in the initial and final animations, which is that
the clip region we normally have for the workspacesView will limit the
animation of the clones to/from the original positions, so we disable
the clip region during these animations.
https://bugzilla.gnome.org/show_bug.cgi?id=643786
When we animating the scale for the thumbnails, the border and
background should wrap around the current size of the thumbails.
The technique that we are using to animate the scale breaks that
since we don't animate the overall size of the thumbnails box -
we just animate our child actors within the allocation.
To fix this, switch from drawing the background by packing in another
container to drawing the background with a separate actor that
is under the other actors and allocated by our custom logic.
https://bugzilla.gnome.org/show_bug.cgi?id=641881
The scale we zoom to in the "zoomed out" mode depends on the width of the
controls area. Once we rescale the workspaces dynamically, we'll need to
update the zoom scale as we add and remove workspaces.
https://bugzilla.gnome.org/show_bug.cgi?id=641879
We will change the workspace thumbnail size as we get more thumbnails; it doesn't
really make sense to always show 1/5 of the thumbnails how big or small they are,
so instead show a CSS-configurable length.
https://bugzilla.gnome.org/show_bug.cgi?id=641879
Fix a bug in the computation of the zoomed-out scale and use a StBin
instead of an unnecessary StBoxLayout. Using the StBin will allow
correct width-for-height behavior for the controls.
https://bugzilla.gnome.org/show_bug.cgi?id=641879
Add WorkspaceThumbnail.ThumbnailsBox to handle managing the array
of workspace thumbnails; the logic will get more complex as we add
scaling and animation.
https://bugzilla.gnome.org/show_bug.cgi?id=641879
Intead of using a St.Group and tweening the position of the controls
actor, use a St.GenericLayout and tween a Javascript property. This
allows us to more reliably track the height of the overall workspace
display and propagate it to the controls actor.
https://bugzilla.gnome.org/show_bug.cgi?id=640996
At the end of a drag operation, we would invoke the code to slide the
controls in (because we were no longer DND'ing and not hovering) and
then immediately afterwards invoke the code to slide it back out when
we got the ENTER event from the end of DND. While the immediately
overridden tween probably won't have any visible effect it's better
to avoid this, so wait to update the zoom state until BEFORE_REDRAW.
https://bugzilla.gnome.org/show_bug.cgi?id=640996
With automatic workspace management, explicit controls to add and
remove workspaces are no longer necessary. We also can remove the
use of addWorkspace for middle-button-click on a launcher since
launching on the last empty workspace will do the right thing.
https://bugzilla.gnome.org/show_bug.cgi?id=640996
With workspace thumbnails, we want to make workspace switching
something that happens largely under the users control, so don't
switch to newly added workspaces in the overview.
https://bugzilla.gnome.org/show_bug.cgi?id=640996
Add workspace thumbnails to the workspace controls area. The user can
click on the thumbnail to switch workspaces and can also drag windows
out of the thumbnail to other workspaces.
https://bugzilla.gnome.org/show_bug.cgi?id=640996
Moving the base tracking of restacking to WorkspacesDisplay will allow
us to use it to update stacking in the workspace thumbnails as well as
in the main workspaces.
https://bugzilla.gnome.org/show_bug.cgi?id=640996
Instead of having a separation between popping the controls out on hover
and zooming out for DND, always do both at once. This is necessary because
when we added workspace thumbnails the controls will get bigger, so we need
to make sure we zoom out far enough so that the windows don't overlap the
controls.
https://bugzilla.gnome.org/show_bug.cgi?id=640996
When checking the type of a DND source, instead of checking
'instanceof Workspaces.WindowClone' accept any actor with realWindow
and metaWindow properties. This will be useful to support a separate
type of actor dragged from workspace thumbnails.
https://bugzilla.gnome.org/show_bug.cgi?id=640996
