setStyle destroy UndoManager

Hi,
during programming I found strange problem with UndoManager related to
textFlow in RichEditableText. When I try to set some style for RET (by
setStyle), all steps stored in UndoManager are reseting.

Here is simple example online:
http://op2.pl/undo/test.swf <http://op2.pl/undo/test.swf>

When enter some text an click "Undo" - everything is ok, but when after
enter text click on "Set Style" (ret.setStyle('backgroundColor',
'#CC6699');) - Undo doesn't work.