Well, to be honest I'm about to start this fall so I don't know the policy of the university and I haven't started any work with my current supervisor. I have heard from of the students with him that he is flexible and supportive in everything except when it come to money. The other professors seem to have a constant funding, but from what I've heard that they tend to be abusive when it comes to other matters. The topic that I am thinking of is a cross over topic (communication systems and power systems) so there is no problem in switching.