Silverlight OpenFileDialog appears behind the browser

Question

In my Silverlight App, I have a button that opens up an OpenFileDialog.

OpenFileDialog oDlg = new OpenFileDialog();
        oDlg.Multiselect = true;
        oDlg.Filter = "Image Files (*.png, *.jpg)|*.png;*.jpg";
        if (!(bool)oDlg.ShowDialog())
            return;

        Add(oDlg.Files);

And then in Add I get the data I need from the FileInfos and go on. The problem I am having is that the window sometimes appears UNDER (or behind) the browser. I've only seen this on Mac. I'd like to get this fixed, but I have no idea where to start. Has anyone seen anything similar or has any ideas?