Using Fileselection, changing or updating labels

["Sandra Derbring" <sandra derbring gmail com>]

This time I have a bunch of questions, I hope to get some good answers from you.

1. Can I change the label of a checkbutton or a radiobutton after I
have created it? I can't seem to find a set_label function for this. Is
there any other way?

2. From my main program, I created a file menu that opens a file
selection box. The fileselection is in an own file and called by with:
o.FileSelection(). When I press "Cancel" on the file selection box that
appears, it doesn't just close itself, but the whole program. How can I
prevent this?
I only want to close the box and return to the main window.

self.filew.cancel_button.connect("clicked",lambda w: self.filew.destroy())

def destroy(self, widget):
   gtk.main_quit()


3. From a file selection box, I want to choose a folder, not a
file. Is this possible? If I try to call methods like file_dir or
file_list, I get the following error message:
TypeError: 'gtk.TreeView' object is not callable

What can I do? Do I have to import something? 

4. I have a window with three boxes. The first with pictures, the
second with parts of speech and the third with definitions of the
words. The parts of speech in the second box are radio buttons. The
definitions in the third are check buttons. What I want to happen is,
that if I choose another part of speech - press another radio button -
the definitions will change. Is there a way to do this? I have tried
many things, but nothing seems to work. Any suggestions? I can show my
code if it is to any help, but maybe someone have an idea anyway. 

Thankful for all tips I can get :-)