The issue is close to 6849774.

Environment: ubuntu, compiz, latest jdk7.

Use the testcase attached to 6849774 to reproduce the problem:

1. The test shows the control frame (with two button) and the tested (undecorated) frame
2. Click the button "Not opaque"

3-a. Sometimes the tested frame correctly becomes transparent // the problem is not reproducible
3-b. Sometimes the background of the tested frame becomes white (not transparent) and the tested frame changes its location (it jumps to the bottom left corner of the screen or the upper right corner of the screen).