[TYPO3] Preview, draft ws and sr_language_menu

[Pascal Cramer]

Hi all,

in a customer's Typo3 installation we have installed sr_language_menu for 
switching between languages. This works fine until we get into the (customer 
specific) draft workspace.
If a (language-restricted) editor tries to preview the work he has done, the 
language switch does not work; it submits the page but does noit switch for the 
selected language: the default language is the only one being displayed in this 
mode.
It makes no difference whether we use the 'View' module or the preview button 
(which also shows the current version)

Does anyone have a clue as to where the cause of this lies?
I am using the correct extension for language switching in this setup?
We are running 4.0.4 and sr_language_menu 1.2.4.

Thanks,
Pascal