I have set the scroll amount to 1 line in mouse settings. With the default 3 lines, Gwenview and add plasmoids scrolled too much. When I set it to 1 lines, Gwenview and add plasmoids were ok, but Dolphin and Konqueror scroll very small amount.

I think the problem here is that Gwenview defines a line as one row of folders, Dolphin and Konqueror define it as one text line. Everything was OK in Dolphin and Konqueror with 3 lines scroll, but then Gwenview scrolled 3 rows of folders and images which is annoying and add plasmoids scrolled 3 plasmoids. I think there are many more examples other than that, that have the scrolling problem.

Btw, I'm using KDE 4.2

Currently, only application specific keyboard shortcuts are available, but advance mouse settings work globally.
This may be submitted as a "wish" to bugs.kde.org