The Content Translation dashboard shows several lists with options to filter them by language. Some views (in-progress and published) initially show content involving any language. However, once the user selects one specific language, there is no way to go back to the original state.
We can add an "any language" option for those cases when it is needed. That is, the option will be only available on selectors that can show content for any language and only when a specific language has been already selected. The option will be shown at the top of the list of languages, not labelled by any group.
A mockup illustrates the idea: