gtk3(mm) under Os X

[C Gosch <ch gosch googlemail com>]

Hi List,

I started using gtk3 (gtkmm-3.0) on OS X, coming from Linux.
I installed everything using homebrew. I noticed that the windows of a very old test program that I wrote are 
having the wrong spacings between widgets and that
some stock icons are missing. That program was last used with gtk2.4, so I am guessing it might be a mix of 
old code and maybe things being slightly different under OS X.
Does anyone on this list have experience with gtk3 in OS X and can give me some hints on how I can use it so 
that it blends well into the rest of the desktop?

Thanks very much!
Christian