TYPO3 Core

Problem:
We developed a flexible-CE-object some years ago giving an editor the possibilty to add 0 to x links via a TV section. This flexible-CE-object also uses an RTE field – outside the section. And this RTE field doesn’t work any longer - I think since we upgraded from TYPO3 4.2.x to 4.4.x.

It permanently shows: „The editor is being loaded. Please wait...“. The debug mode of RTE only shows:
[HTMLArea::init]: Editor url set to: sysext/rtehtmlarea/htmlarea/
[HTMLArea::init]: Editor skin CSS set to: sysext/t3skin/rtehtmlarea/htmlarea.css?1298470801
[HTMLArea::init]: Editor content skin CSS set to: sysext/t3skin/rtehtmlarea/htmlarea-edited-content.css?1298470801

In normal content elements (e.g. text or image with text) the problem doesn’t occur.

Reason of this problem:
First a thought this problem is produced by the section - if I delete section, RTE works perfectly again. I asked RTE-expert Stanislas for help. He says:
"This is not a RTE issue. A js error is raised in jsfunc.tbe_editor.js while checking for required elements. The error interrupts inline JavaScript execution before initialization of the RTE is invoked. This explains why the RTE is not loading."

To get a working RTE I don't have to delete the whole section, it's only necessary to delete "<eval>trim, required</eval>" which is used in one of the input fields in the section. Without "required" all works fine again!
Don't tested if this issue occurs only in sections.

Attached the XML-code of the data structure. Kine 517 is the "problem-line" - it is commented out.
(issue imported from #M17899)