how to make a button not close a gtk_dialog?

[Joergen Scheibengruber <Joergen Scheibengruber informatik uni-ulm de>]

Hi!

I am currently adding a help to my gnome application. And I came accross
a little problem: I added a help button to my dialogs, which were
created with gtk_dialog_new_with_buttons(). Everything works fine, but
when the user clicks the "help" button, the dialog gets closed. But in
case of the "help" button, I want to keep the dialog open ("cancel" and
"ok" shall of course not change behaviour).

Is there an easy way to achieve this? I can't seem to find any in the
gtk documentation...
What would you suggest?

Greetings,
Jörgen