How is scrolling supported in Linux graphical environments like GNOME and KDE?

I'm curious to know: is scrolling (such as in Firefox, Nautilus, etc.) handled be each application separately? Or is it done by the environment? Or by the widget toolkit?

What confuses me, is that it is possible to change to "smooth scrolling" in Firefox, which makes it seem like each application handles its scrolling separately. However, when writing software for Linux, you don't really need to specify and it seems like GTK takes care of it on its own.

The reason I'm curious is because I wanted to know if Linux could have it's own "accelerated" scrolling, much like OS X. I know this is possible by app, because Goog开发者_如何转开发le Picasa has its own built in.

To make this possible for the entire system, does GTK need to be modified? Or something else?

1. Most applications rely on their toolkit for scrolling behaviors.

2. Firefox does a lot of stuff by itself, partly because it runs on various platforms with various toolkits (not just GTK), and partly because it has advanced needs that aren't always met by whatever toolkit it happens to be using.

3. GTK is far from the only toolkit used on Linux. There is also Qt (which is used in KDE), wxWidgets, Tk, FLTK, Motif clones, Xt, and you can even build applications on Xlib itself without a toolkit.

4. You're using two different terms, "smooth scrolling" and "accelerated scrolling". These are not the same thing, and the latter is technically ambiguous.

5. There is absolutely nothing preventing Linux (really X) applications from having any particular scrolling behavior. It's up to the application and/or its toolkit, if it relies on one.

6. Regardless of the above, keep in mind that not everyone agrees that the scrolling behaviors you allude to are good.