Keypad navigation focus is hard to see with big QPushButtons on Symbian

Currently keypad navigation focus is a thin rounded rect around widgets.
In some themes, even if the theme color is properly used, the rect is rather hard to see
if the surrounded widget gets near the focus rect.

Instead of round recting with "empty" rect, we could fillrect the area from outer rim of
focus rect to outer rim of widget (see buttons_with_focus.png)

This would be easier to spot.