TYPO3 Core

when the user edits a file in fieladmin and checks the "deactivate t3editor" checkbox below the t3editor, this state won't be stored correctly.
So the t3editor is still actived, when the user edits a file next time.
In the template module this setting ist stored in the user configuration of the backend user.

Reason:
When saving a file in file_edit.php the POST-request is send to tce_file.php, which then redirects back to file_edit.php.
In file_edit.php the class tx_t3editor is instanciated. This class checks, if the checkbox is set in the _POST values. Due to the redirect these _POST values are no more available.

Solution:
Use ExtDirect to store the user configuration value.

(issue imported from #M17268)