如何在DoDragDrop中重新绘制UI

I'm implementing my app as a drag source. When I call DoDragDrop (Win32 call, not MFC) it enters into a modal loop and I don't get repaint messages in my main window until DoDragDrop returns. Unfortunately if I do a drop in the shell (a file) and the filename is already there the shell asks if I want to replace the file. But since me app is blocked because DoDragDrop hasn't returned it isn't repainting and looks 'frozen'. I'm implementing my app as a drag source. When