Created attachment 358020 [details] [review]
workspace: Fix tab navigation order

By default the focus chain uses the same order as the list returned
by clutter_actor_get_children(), which corresponds to the z-order.
This doesn't work well in the window picker, where clones follow
the stacking of windows to ensure a correct overview transition,
but previews are laid out purely based on space efficiency. As
a result, the order in which window previews are navigated when
tabbing around is essentially random. Fix this by providing a
focus chain implementation that is based on the visual layout
of the previews rather than the stacking.

Created attachment 358021 [details] [review]
workspace: Focus clone when highlighting

We don't use different hover- and focus indications for window previews,
so using keyboard navigation after hovering a clone often has surprising
results when the previous focus window wasn't the selected one. Address
this by simply moving the keyboard focus with the highlight.

Review of attachment 358020 [details] [review]:

ok looks fine

::: js/ui/workspace.js
@@ +1074,3 @@
+            let cloneB = (b._delegate && b._delegate instanceof WindowClone) ? b._delegate: null;
+            if (cloneA && cloneB)
+                return cloneA.slotId - cloneB.slotId;

can't happen with the way the code is right now but slotId should probably be initialized in WindowClone to be safe

Review of attachment 358021 [details] [review]:

ok

Attachment 358020 [details] pushed as 8143f73 - workspace: Fix tab navigation order
Attachment 358021 [details] pushed as 1939e22 - workspace: Focus clone when highlighting