MGNLUI-3491 fixed an issue with validation being skipped for non-active locales in dialogs by forcing an user to meet all the requirement before switching the locale of the dialog.

However that brings a new set of issues since inability to use the locale switcher is limiting for editors. Two use-cases:

• even though there's always a fallback locale it doesn't have to be filled for a particular node, in that case it's impossible to fill other locales if there are required fields in place.

• if editor writes a content in the fallback locale and switches to other locale, it's impossible to go back and/or save the content if there are any required fields.

This can of course be avoided by dividing the content into multiple trees but not every time is this solution possible.

Ideally the validation should be performed for all locales during the save dialog step.