-5

Visual integration of kwin and plasma could be improved if it was possible to use plasma tooltips. This would mean that the appearance when hovering over something in an application would be the same as something in a panel.

This has nothing to do with KWin (the window manager)

Application tooltips are painted by the (oxygen) UI style.
Why there needed to be an extra styling/theming mechanism for plasma i don't know, so please don't ask - i'd certainly start a rant otherwise.

KWin is a windowmanager
Plasma is a graphical desktop

Either one doesn't have anything to do with each other or application tooltip what is depending of Qt style.