If a modal window is closed, usually, it will go behind its parent. The
reason for this is that Workspace::constrainedStackingOrder() puts only
AbstractClient transients above parents, not Deleted transients.
So, if fade/glide/scale effect animates the disappearing of a transient,
unfortunately, one can't see that animation.
BUG: 397448
FIXED-IN: 5.15.0