Re: SetClipboardViewer()

Thanks joe.

If I launch clipbrd.exe firstly before my app, Yes, SetClipboardViewer()
returns a valid handle. By Spy++, I can confirm it is clipbrd's handle.

And then, I copy something by NOTEPAD or MSPAINT, by CMyDlg::WindowProc(UINT
message, WPARAM wParam, LPARAM lParam), I can catch WM_DRAWCLIPBOARD
message.

After that, I exit clipbrd, I fail to catch WM_CHANGECBCHAIN message.

I think it is not necessary for a clipboard viewer to be a top window(CMyDlg
is a child-window).

Another question: should I return (LRESULT) NULL or call
CDialog::WindowProc(message, wParam, lParam) after dealing with
WM_DRAWCLIPBOARD /WM_CHANGECBCHAIN as follows,

LRESULT CMyDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
{
     if ( message == WM_DRAWCLIPBOARD )
     {
          UpdateClipSizeShow();
          ::SendMessage(hNextWnd, message, wParam, lParam);
          //Should I return NULL here?
          return (LRESULT) NULL
     }
     else if ( message == WM_CHANGECBCHAIN )
     {
          if (hNextWnd == (HWND) wParam )
               hNextWnd = (HWND) lParam;
          else if (hNextWnd != NULL)
           ::SendMessage(hNextWnd, message, wParam, lParam);

          //Should I return NULL here?
          return (LRESULT) NULL
     }
     return CDialog::WindowProc(message, wParam, lParam);
}

ou