And for several large programs they are. As media players have been discussed recently: iTunes, Windows Media Player, Winamp all use non-standard interfaces.

And for several large programs they are. As media players have been discussed recently: iTunes, Windows Media Player, Winamp all use non-standard interfaces. Browsers have varying degrees of deviation from a "standard" program with Chrome being the worst. LibreOffice and OpenOffice before it both have some atypical components. I could go on.