What would be the simplest way to list all menu items - independent on the current language and still keep the "Content selection" to "Only current language". Or maybe an AJAX refresh when other language is chosen in dropdown menu.
My clients usually have multilingual website but they don't want to use CMS interface in that language (and it would be rude from me to force to use multilingual user interface). When they want to add a new page to an English parent item (i.e. a page) in menu they would need to go to /en/node/add/page but their primary language is not English.
The same goes with taxonomy, there are no terms available on node form if Drupal is in other language if "Only current language" is set on Content selection settings. But it has to be set that way so site visitors get only one language on the specific prefix path (i.e. /en/).
Many other CMS have back-end in only one language, and when choosing language on drop down (while editing) dependeding input fields like menu or categories get updated and only hold items of the same language.
I know that is impossible in Drupal because back-end is front-end but did someone discover a way to achieve a similar effect.
One think I was thinking about was not to use Locale or i18n. So I would create SL, EN and DE root elements in the menu or vocabulary and then wrote custom queries in themes.