TYPO3 Core

In TYPO3 4.6 and 4.6.1 inline records in TCAform might break tabs.

If an element in the form has an inline relation to tt_content and the record is opened, no tab in the parent element can be used. Every clicked tab is rendered as active and stays that way when selecting other tabs.
The content of each respective tab is simply added to the bottom of the tab containing the inline element.

However, this only happens when the inline element contains tabs itself (hence tt_content in the demo). When using some other table without tabs of its own as an inline element, everything works as expected.

TYPO3 4.5.x works as expected.

Demo Extension How-To:
Install the extension and create a new "Error Demo" record in List View.
Open the new record and create a new inline record within.
Try to select another tab.

The bug occurs in several browsers (Opera, IE9 and Firefox) and both TYPO3 4.6 and 4.6.1.