Continuous stream of WM_PAINT messages to main Form in Windows 7

Hi,

I'm facing a very strange issue in Windows 7 64 bit machine. I have an application(Win Forms) which runs perfectly fine on Windows XP. Recently, I had to port this application to Windows 7 which we did successfully. Everything works as expected, but my main UI (form) get  continuous stream of WM_PAINT message. After very long analysis identified the root cause. In my application, I have overridden CreateParams property of main form to avoid the flickering issue (code is given below). Somehow, this causes the continuous stream of WM_PAINT messages to main form. Application works fine(with flickering, but continuous WM_PAINT stopped) after commenting our this code part.

protected override CreateParams CreateParams

{

   get

   {

      CreateParams cp = base.CreateParams;

      cp.ExStyle |= 0x02000000; //WS_EX_COMPOSITED

      return cp;

   }

}

I managed to create a test application which reproduces the problem quite easily. The test application is simple Windows form application. In the main Form, I placed a property grid control and bound to Form object itself.  I also overrode the CreateParams property of the form as mentioned above. That's it.

While running the test application, select one of the item in property grid control. This will cause infinite WM_PAINT messages to the main Form. As soon as the selection moved to any other control in the form, this WM_PAINT stream stops.

I would like to know couple of things:

1. What is the real root cause of this problem ? (I have fair understanding on the difference in UI rendering in both XP & Win7. I would like to know the reasons beyond that.)
2. How can I solve this issue ? (Any solution which won’t cause UI flickering and continuous WM_PAINT messages will help.)

Any help in this regard will be much appreciated.

Thanks