This page is being performed while I'm porting Typing Turtle Activity to Gtk3.
There is a [ticket] with some useful information that I'm using on the porting and to keep tracking this port. Besides, this wiki page will be useful to write some code snippets about what are the difficulties that I'm having on the port and maybe can be useful for someone else.
I will take this guide as reference on the Gtk3 porting.
gc = self.get_style().fg_gc[Gtk.StateType.NORMAL]
gc = self.get_style().fg[Gtk.StateType.NORMAL]