This allows whatever the user calls from the signal handlers to react to observe
the new state rather than the old, e.g. that a surface is no longer mapped in
the unmap handler.
wl_subsurface description states:
A sub-surface becomes mapped, when a non-NULL wl_buffer is applied and
the parent surface is mapped.
Note that this doesn't require an explicit commit, which means that a
newly created subsurface with a mapped parent and a buffer already
attached must be mapped immediately. This can happen with the following
sequence of events:
- subcompositor.get_subsurface(subsurface, surface, parent)
- surface.attach(buffer)
- surface.commit()
- subsurface.destroy()
- subcompositor.get_subsurface(subsurface, surface, parent)
Fixes: https://gitlab.freedesktop.org/wlroots/wlroots/-/issues/3449
wl_subsurface::set_desync description states: "If cached state exists when
wl_surface.commit is called in desynchronized mode, the pending state is
added to the cached state, and applied as a whole."
This commit reintroduces an implementation of said behavior, previously
removed in 7daf6da9ac05be2cb74c0983e3caee0b21db75d4.
Strictly speaking, this logic isn't fully correct, as the cached state
and the pending state are applied individually instead, if the cached
state isn't locked by anything else. However, the end result is still
the same.
This commit fixes the issue with Firefox permission popups.