Do not reuse button_toolbar instance
Do not reuse button_toolbar instance

After rendering BuildingLevelRoomTable for the first time its lazily
joined toolbar class variable will be exhausted. Therefore, every
following rendering attempt is going to fail.

lukasjuhrich/pycroft,agdsn/pycroft,lukasjuhrich/pycroft,lukasjuhrich/pycroft,agdsn/pycroft,lukasjuhrich/pycroft,agdsn/pycroft,agdsn/pycroft,agdsn/pycroft