Sorry, my fault :-(

I'm aware of the issue (since yesterday) and will get to it after the weekend at the latest - it's that none of the possible fixes I've come up so far convinces me too much ...

Created attachment 297968 [details] [review]
messageTray: Fix actor visibility

The actor is supposed to be hidden while no notification banner
is displayed, and in addition to that when banners are temporarily
blocked (because the calendar is open). However the current code
always shows the actor when banners are not blocked, fix that.

Created attachment 297969 [details] [review]
messageTray: Take over trayBox from LayoutManager

Since commit e189a34, the trayBox uses a Contraint to cover the primary
monitor's work area. This allows banners to be clipped so they don't
leak into monitors above the primary one during animations. However even
without being reactive, the trayBox now interferes with operations like
Looking Glass' object picker and overview DND.
With the trayBox no longer being positioned manually, there's no strong
reason to keep it in LayoutManager, and handling it in MessageTray allows
to hide the actor while no banner is showing, which helps with the issue
outlined above.

Created attachment 297970 [details] [review]
messageTray: Hide from picks during DND operations

As it is impossible to interact with notification banners while a DND
operation is ongoing, we can temporarily hide the banner container from
picks so that DND works as expected even while a banner is showing.

Review of attachment 297968 [details] [review]:

LG.

Review of attachment 297969 [details] [review]:

LG.

Review of attachment 297970 [details] [review]:

::: js/ui/messageTray.js
@@ +1568,3 @@
+                              Lang.bind(this, this._onDragEnd));
+        Main.overview.connect('item-drag-end',
+                              Lang.bind(this, this._onDragEnd));

Shouldn't this be done for xdnd drags as well?

(In reply to drago01 from comment #7)
> Shouldn't this be done for xdnd drags as well?

Makes sense, yes - I added that before pushing.


Attachment 297968 [details] pushed as 5f5dc83 - messageTray: Fix actor visibility
Attachment 297969 [details] pushed as b3a96f2 - messageTray: Take over trayBox from LayoutManager
Attachment 297970 [details] pushed as d564117 - messageTray: Hide from picks during DND operations

*** Bug 745573 has been marked as a duplicate of this bug. ***

*** Bug 745641 has been marked as a duplicate of this bug. ***

*** Bug 745635 has been marked as a duplicate of this bug. ***