QScrollArea: ensureVisible and ensureWidgetVisible use a big default value for xmargin and ymargin, which makes the result of focusRect very wrong

In QScrollArea::ensureWidgetVisible, it adds a big margin to the focusRect, so the focus rect is incorrectly out of the visible rect, which causes that scrollarea unnecessarily scrolls to right-bottom of the inner widget.
Please modify the default value of xmargin and ymargin to a small value ( maybe 0 is more appropriate).

The attached example can be used to reproduce the following problem:

• press "Start" button in "4 Table", the whole inner widget jumps to a minus left-top position.