Allow using ajax and non-ajax actions in the same actions widget

The actions widget displays all actions within the same form.

When the form is ajaxified, non-ajaxifiable actions do not work as expected (download and print actions for instance).
=> find a way to make some of the actions in a standard form (maybe use a different form for each action for "toolbar actions" widget, and not for "form actions" as in this case they all need to be in the same form).