Resize background color

I h开发者_如何学Goave a Windows app for which when the window is quickly made bigger pieces of "whitespace" are temporarily created.

Is there a way to make those pieces of whitespace black?

You can set autoFillBackground property of the window and have Qt paint the newly exposed background for you. There are some Windows specific attributes mentioned there, too. Mainly, WA_NoSystemBackground needs to be set to use a different background color.