As it was "impossible" for Apple to decide when all they had was the old Macintosh toolbox and NextStep UIs, but they did it. They made Carbon/Cocoa to look rea

As it was "impossible" for Apple to decide when all they had was the old Macintosh toolbox and NextStep UIs, but they did it. They made Carbon/Cocoa to look reasonably consistent despite huge internal differences. Linux can do the same with Qt/GTK+/etc. It certainly possible to have high-level UI consistency between multiple toolkits, especially when they all share the same lower-level stuff (X11/Cairo).