QMdiArea does not paint the setBackground image correct when it is being scrolled.

When QMdiArea::setBackground is used to set a background image, and if vertical or horizontal scroll bar is used, it leaves some artifacts.

Updte: Scrolling is not required
QMdiArea::setBackground(myRedBrush) does not work unless windows is not resized.
Attached example reproduces this, Steps:
-Run application and click new to open new sub window
-click menu change color
-Observe background color does not chagne,
-Move sub window, observe trail of new bg color
-resize main window, new back ground color comes in effect