Insert one additional call to pladv to solve undefined background colour issue.  
Insert one additional call to pladv to solve undefined background colour
issue.  

I don't have any deep understanding of why this extra pladv call is
necessary, but I tried propagating this fix for the same issue from
qt_example.cpp to pyqt4_example.py, and it worked.  Therefore, I am
committing the fix.


svn path=/trunk/; revision=10204

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