Windows Forms User Control not visible when hosting it in Dialog

Question

I have a Windows Forms control hosted as Child in WindowsFormsHost in my WPF application. Control draws ok in main frame. But when I add it (exactly the same way) in WindowsFormsHost on dialog that is shown from main frame, on ShowDialog the control is not visible. I used the same code as I did with main form. When debugging, it does every line of code like drawing control in main frame, but control is still not visible in dialog. What could cause this problem?

Answer 1

Ok, after some testing it turns out that Windows Forms Control is not painted in dialog window if Window's Allows Transparency property is set to True. Any ideas now?