This is reproducible on WinNT4 and RedHat Linux 6.1 using the TreeDemo of SwingSet2.

To reproduce:
* bring up the TreeDemo
* fully open one of the branches
* drag the SwingSet window off of the bottom of the screen
* slowly drag the window back onto the screen. An erroneous column of pixels is painted for each exposed "level" of the tree.

This was introduced somewhere in merlin beta b45.