TYPO3 Core

After upgrading from typo3 version 3.81 to 4.15 floating problems with embedded RTE´s (with felxforms) occur. Active sheets (active JavaScript) are displayed correctly. After page/frame reload dimensions of RTE´s are correct, but they are overlayed in display after switch to an other sheet.

This impact can be reproduced only with Firefox 2.* and TYPO3 in version 4.1.*. Internet Explorer 6 and above? will not be affected.
Tests with TYPO3 Version 3.8.1 seems to be not affected.

An HTML source code dump shows no differences between correct and wrong drawn sheet. So i think, it has something to do with the javascript code for switching the active sheet.

Some other users have the similar problems:
http://www.typo3.net/forum/list/list_post//73438/?page=1
http://bugs.typo3.org/view.php?id=6706

The picture in the attachment shows the correct and wrong sheet display.
(issue imported from #M7530)