Part of changes proposed in #117285. Unfortunately layout panels aren't supported in popovers, so this has been worked around using a kludge that stores the expanded state as a class member, toggled via "wm.context_toggle".
Part of changes proposed in #117285. Unfortunately layout panels aren't supported in popovers, so this has been worked around using a kludge that stores the expanded state as a class member, toggled via "wm.context_toggle".