Activate a widget then set the focus on it

Adding a function activate_focus()
I don't think that always stripping texts here is a good thing. If you *really* need that, I'd prefer an optional argument for the method like:

def set_current_text(self, text, strip=False)

with a default to false to keep compatibility. If you do that, I would like it to be present in another commit to keep things simple. :)