[7u4-osx] Request for approval for 7125723: [macosx] painting artifacts after running SwingSet2 with jdk7u-osx build

[Dmitry Cherepanov]

This is a request to push the following fix to jdk7u-osx:

CR: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7125723

Webrev: http://cr.openjdk.java.net/~dcherepanov/7125723/webrev.0

Technical review: 
http://mail.openjdk.java.net/pipermail/macosx-port-dev/2011-December/001976.html

Thanks,
Dmitry