I just got here, but I was successfully able to build Gonstruct on 10.10.1 with absolutely NO problems at all. I did a pull request for the readme as you need to install "gtksourceview2", not "gtksourceview", but once that's done, as long as you do everything right, it should compile with 0 errors and 0 warnings.
If you have xquartz and maports installed, you should be able to just run this:
git clone
https://github.com/fry/graal-gonstruct.git
sudo port install gtkmm
sudo port install gtksourceview2
sudo port install gtkglarea2
sudo port install boost
sudo port install cmake
cmake .
make
src/level_editor/gonstruct
And about 30 minutes later, you should be done.
Side note, your "Graal Directory" will be ~/Library/Application Support/Graal