How important is it for an application to be consistent with the native Operating System? And exactly what does that mean?
This is brought on by work on a new default theme for Firefox, in a peripheral fashion. In a lot of the talk I read about User Interface design focuses on having the app be consistent with the OS's look and feel.
I think a lot of this started with Macs. Mac users are near-fanatical about how great the interface is on their OS. While a lot of it is eye candy, that doesn't make a very convincing argument. So the other facet they can trumpet is the consistency and intuitiveness of the interface. So, as great cross-platform applications come out that Mac users wished to use, they had to complain about the inconsistent look. How these apps just didn't fit in.
The phrase, however, is look and feel. It seems to me that only the "feel" needs to be consistent. The purpose is for user's to be able to use your application without any difficulty. But this isn't enough to make those Mac user's happy. But at least for those of us on Windows or Linux, we have a variety of apps that look quite different. Not even all Microsoft apps look like each other: how similar is Windows Media Player 9 to Internet Explorer 6?
In fact, of course, a unique look for an application is a major branding advantage. You want your application to be memorable and identifiable. Additionally, you want it to by stylish. It's not easy to accomplish that while trying to make your application "fit in" with the OS. Not to mention, what exactly does that mean? It seems in the case of the old Firefox theme, it meant copy the look of the default browser of that OS. Does it make sense to let your competitor define how your application should look?
So far, my conclusion is that most OS's (or desktop environments), such as Windows (which one? 95, 98, 2000, XP, Longhorn?), KDE, or Gnome, haven't yet achieved real consistency anyway, so over-worrying about "fitting-in" should not be the primary concern in UI design at the moment. What do you think?