Windows Forms User Control not painting well in WPF application

Question

So, this is the issue: I have a Windows Forms User Control that I placed in main Window of my WPF application. I override paint method of User Control. It paints ok in "ideal" case. But, after showing the control in main window, I added MessageBox. This is the code snippet:

board = new BoggleBoard(Boggle.CurrentGame.Size);
        boardHost.Child = board;
MessageBox.Show("You have " + time + " seconds to find as many words as you can. Click OK when you are ready to play);

If I don't show MessageBox, everything is ok. But with the code above, after MessageBox is shown, my control is painted, but just like boardHost (Windows Form Host) has lower opacity, so I get dark area around the control. I say "like" cause I tried with

boardHost.Opacity = 1;

but it doesn't help, I still get the same thing. What might cause this problem?

Answer 1

Here is a screenshot. As obvious, the dark area around the board should not be there. And it is not visible if I don't show MessageBox after it is drawn.

http://i.imgur.com/RZs2W.png