How to get a normal application menu in the top- or titlebar in Gnome
Solution 1:
I guess Gnome Global Menu Extension is what you're looking for.
It was a work in progress back in April (see OMG Ubuntu), some applications would work, but there were problems with others (like Blender). Don't know what's the current state, but if you feel like giving it a try, detailed install instructions are to be find in GitHub.