Hello!
After last changes on 1.28 for GTK3, in trying once again to be if I could move to Geany with GTK3 , which I prefer over GTK2.
One thing I've noticed is that the colours of the toolbar does not match with the colours of the rest of the interface. Here is a snapshot of my Geany with GTK - 3.0: 
I'm on Ubuntu 16.04 with Ambiance theme.