f3420b0341
Commit cda9579034b fixed a corner case when setting the initial workspace
state of transient windows, but it still missed a case:
should_be_on_all_workspaces() returns whether the window should be on all
workspaces according to its properties/placement, but it doesn't take
transient relations into account.
That means in case of nested transients, we can still fail the assert:
1. on-all-workspaces toplevel
2. should_be_on_all_workspaces() is TRUE for the first transient's parent,
as the window from (1) has on_all_workspaces_requested == TRUE
3. should_be_on_all_workspaces() is FALSE for the second transient's
parent, as the window from (2) is only on-all-workspace because
of its parent
We can fix this by either using the state from the root ancestor
instead of the direct transient parent, or by using the parent's
on_all_workspaces_state.
The latter is simpler, so go with that.
https://gitlab.gnome.org/GNOME/mutter/issues/1083