Fixes the issue most noticable with klipper's text field not having
focus; though use of debug rectangle showed it affected all applets.

Plasma popups get focus, which is given to our StackView, because that's a
focus scope that will give activeFocus to the focussed item within that scope.
However, nothing was explicity set, so nothing got focus.

Debug rectangles followed by checking the original bug of opening klipper twice and on
both occasions typing immediately went into the text box