Toggle button in listitem - how to stop event

[Lars Clausen <lc statsbiblioteket dk>]

Hi!

I have a GtkListItem that contains a GtkToggleButton and a GtkLabel. 
I'd like it so that when the user clicks the label, the listitem is
selected, but when the user clicks the button, the button toggles
without the listitem selection changing.  Currently, the listitem gets
selected by the button click as well.  How can I stop the button click
from falling through without reimplementing button event handling from
scratch?

For the curious, this is the connectable button in app/layer_dialog.c in
the DIA_0_94_DEVEL branch of Dia CVS, and the selectable button shows
the desired behaviour, but is an awful hack.

Thanks,
-Lars