Naming classes is not simple, hence the multitude of methodologies (BEM etc) that try to define a structured way of doing it. So... it's logical that during developement we sometimes change our mind about a class name. It would be nice if we could globally rename a class. Something like search and replace for classes.
I think since BSS keeps html "locked" and "under control" it would be fair not to rob us of this convenience of a simple text editor. :) Ideally, this "rename class" function would rename the class both in html and css (or scss).
+1, I've thought that for a long time that it would be nice if a class name was changed if it would locate and show us all the instances in all the pages that a class is on so we know exactly where we need to go for changing them. That alone would be good enough for me as I don't think I'd want it to auto change them all automatically. Only because maybe I will want to remove it from some areas instead of altering the name, and this way I can do them myself so I can alter only those I want to alter.
Maybe to go a step further have it locate all the classes in all the pages, then give us a dialog for each asking if we want them all changed, or if we want it to go through and change only those we tell it to (like a normal find/replace would give us in pretty much any other text editor). This way we would have the ability to auto change them all if wanted or just have it auto change them one at a time where we say yes/no and it moves to the next one till it's cycled through them all.
I agree with @jo, but I would assume that @psithu would be thinking more like you have an option to "Replace All" and a option for "Next" to move to next instance of entered class with an option to "Replace" so you can skip over some instances of the class. This would be an idea where you could delete the class or rename one of more of the searched class.