Currently, the workspace swipe transition only has one workspace in each
direction. This works until you try to do multiple swipes in quick
succession. The second swipe would continue the existing transition, which
only has 2 or 3 workspaces in it, and will hit a wall.
To prevent this, take all workspaces and arrange them into a column or row,
depending on the layout, and use that as a transition.
For the transition that happens when focusing a window on another workspace
(for example, via Alt+Tab), still use only two workspaces instead of all of
them.
Since we don't support layouts other than single rows/columns anymore,
diagonal transitions aren't supported anymore, and will be shown as
horizontal or vertical instead.
Since nw alt-tab and gesture transitions are different, don't allow to do
both at once, that is, disable swipe tracker when a programmatic transition
is going. This will also conveniently cancel a gesture transition if a
programmatic one is initiated while a gesture is in progress.
Fixes https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/2612
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1326>
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