Installed version: SM v1.5.2SVN (20110716)
I'm opening a new message for reading. Then I decide to forward it to an other person and press he Forward-button. After that I press the Addresses-button to select the new receiver of the message. Right after the button has been pressed the message text is shown twice above and below the address search window. I've attached a screenshot which shows the effect to this report.
This error can be reproduced on different servers.