[gtkmm] enter key press into an entry of dialog box

[cedric <cedric probesys com>]

hi !
i've made a small dialog box which asks for login and password to enter 
into my application.
So i get the vbox of the dialog box.
and i pack into it : 
a label, a frame containing the login entry and another frame containing 
the passwd entry.
And 2 buttons OK and CANCEL
buttons work well :o)

My problem is :
I would like to activate the response of the dialog box (as well as push 
OK button) when i type ENTER KEY into an entry.
Cause it's very bouring to click on OK each time you enter your login 
and password ...

I've tried to find a way to do that but the frames are not activables 
and i need the frame to put a label in it :
--password:----------
|   root                    |
----------------------------

Thanks !