Using pdb for debugging python with multiple frames

[Bob Doolittle]

Hi,

I'm new to python mode in emacs. I generally like to work with multiple, 
full-height frames. I find that when I do M-x pdb it always splits my 
frame between the source and debugger buffers. Even if I close the 
source window and display the source buffer in another frame, as soon as 
I do any command in the pdb buffer it re-splits that frame.

It's much more useful to me to view source in a separate, full-height 
frame. How can I stop this frame-splitting behavior with pdb?
I'm afraid I'm still using GNU emacs version 21.3.1 with python-21.el 
and hope this isn't going to force me to upgrade immediately...

Thanks,
  Bob