This is a larger clean-up of the refresh situation.
The general shift is that refreshes are now mainly triggered by
the (top-level) widgets when they get shown or closed via UIManager.
All refreshes for the widgets when they are in use were handled by
themselves before. This adds the case of showing/closing.
It is the desired result of not having UIManager:show()/:close()
do (full screen) refreshes on its own.
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