Set ToggleToolButton Icon to Pixbuf

[Fatum Legion <fatumlegion gmail com>]

Hi there,

I've got a simple function that looks like this: http://pastie.org/8654221

This seems to work OK if it's called from the Window's constructor, but if it's called from anywhere else (i.e. a clicked signal) the icon disappears completely. 

Any ideas what could be going on here?  Thanks for any help!