[Bug 9875] New: moving dialogs shows artifacts on window behind it

http://bugs.winehq.org/show_bug.cgi?id=9875

Summary: moving dialogs shows artifacts on window behind it
           Product: Wine
           Version: 0.9.46.
          Platform: PC
               URL: http://ftp.ldscatalog.com/PAF5AllLangs.exe
        OS/Version: Linux
            Status: NEW
          Keywords: download
          Severity: normal
          Priority: P2
         Component: wine-x11driver
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]

Start PAF, and go to the "Family" view.
Open any dialog in PAF, or any other application that makes a new top level
window.  When moving that window around, it leaves trails of itself on the
family view in PAF.  I have to minimize PAF and restore it or equivalent to get
the window to refresh itself.

If you move the window slowly, one pixel at a time, it doesn't happen.

I put some printouts in X11DRV_Expose() and BeginPaint() and noticed that when
the two are called in turn, things are fine.  If X11DRV_Expose is called twice
or more before BeginPaint() for the family view, the trails start showing up.

Any ideas out there?