I'll admit I haven't seen the NT source but from a user perspective NT's UI (widgets, progman, etc) looked and functioned near identically to Windows 3 so I've

I'll admit I haven't seen the NT source but from a user perspective NT's UI (widgets, progman, etc) looked and functioned near identically to Windows 3 so I've always thought those bits were ported over. I'm aware most everything under that was replaced. To my eye that was one step in a well-executed evolution up from legacy Windows towards the eventual convergence in XP.