[xorg-bugzilla-noise] [Bug 1030] New: New damage sprite is duplicated when scrolling (XCopyArea)

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https://freedesktop.org/bugzilla/show_bug.cgi?id=1030        
   
           Summary: New damage sprite is duplicated when scrolling
                    (XCopyArea)
           Product: xorg
           Version: CVS_head
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Server/general
        AssignedTo: xorg-bugzilla-noise at freedesktop.org
        ReportedBy: krh at bitplanet.net
                CC: keithp at keithp.com


With the new damage based sprite, sometimes when scrolling a document under the
sprite, the sprite image is duplicated.  To reproduce, scroll almost to the end
of a document in e.g. firefox.  Leave the last half screen of the document below
the window.  Place the cursor in the lower half of the document window and press
page-down.  The point is that the cursor should be above a part of the document
that will still be visible when the document is scrolled, and after scrolling,
the cursor should be over a part of the document that was not previously visible.

The problem must be that the sprite code does not receive a damage callback for
the source area of a XCopyArea().  This makes sense, but then it is not able to
remove the sprite before the area is copied, and the sprite is copied with the
area.  If the sprite also intersects to destination area, it works fine because
the sprite code receives a callback in this case; this explains the behaviour
described above.        
   
   
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