Polygon2D editor might persist when node is unselected

[KoBeWi]

Godot version:
3.2

Issue description:
When you create a (Collision)Polygon2D node and edit it and then unslelect the node via scene tree, the polygon lines are still visible until the viewport is redrawn (e.g. until you move your cursor inside).

This seems to happen when a vertex is selected.

Similar case is when you "unclick" the polygon, i.e. click outside it when it's selected. The node isn't selected in the scene tree, but the polygon can still be edited.

[KoBeWi]

Still valid in 3.2.4 beta4
#43223 will partially fix it, but the viewport still isn't redrawn properly on deselect.