Change Emacs window size

[Alexander]

Hello.
I would like to know, how to change emacs' frame (X11 window) size on 
the fly.
I've discovered function x-send-client-message in emacs, which is used
to make emacs full screen, but all my tries to make emacs frame a little 
smaller
or a little larger did not have any result.
I've tried to do so, but it does not work
*(defun toggle-fullscreen ()
  (interactive)
  (x-send-client-message nil 0 nil "_NET_MOVERESIZE_WINDOW" 32 '(100 
100 40 40))
)*

Can anybody help me?
Thanks.