It is important to notify users of any changes that will happen before the user activates the form control. This is important for any controls, but particularly important when it causes a change of context, such as a page refresh or a change of language.
If a form control causes something to happen when a user tabs into it, make sure this is clearly indicated before the control. This can be as simple as a text instruction that says "Opens in new window" or "This will change the current language of the webpage". If the user will be unable to use the "back" button of their browser to return to the current webpage, make sure this is clearly explained.
No example is available.