Hi,
I've recently decided to try KDE 4.1 on my Kubuntu 8.04 box.
Although it looks very nice, it seams that some applications ( Firefox 3.0.1 and Gimp 2.4.6 for example) aren't visually integrated with KDE 4.1.
I haven't had such problems with KDE 3.5.10.

Now, I'm not sure why this is happening: It's a KDE problem or do I have to make some setups?

Thank you

KDE is built with QT. Firefox and Gimp are built with GTK. Under KDE 3.5 the package gtk-qt-engine does some stuff that applies your current QT theme to GTK apps. For KDE4, look and see if you have the package gtk-qt-engine-kde4 installed.

Thank you,

It does seem to make things look better.

Instead, I would use qtcurve.

Qtcurve is a widget style/theme that has native versions for qt 3.x, qt 4.x and gtk 2.x. This means that all the apps using these toolkits will look virtually the same. And the style will be native, and not emulated like this of gtk-engines-qt or whatever your distro names it.

The emulation of gtk-engines-qt is far from perfect, and native engines always perform better.

I've tried both the qtcurve and geramik themes, and both of them caused strange icon changes in iceweasel. For example, my bookmark toolbar button gets changed to a back arrow. Only the gtk-qt-engine works correctly. Unfortunately, audacious complains about gtk-qt-engine, saying it's "broken". It would be nice if there were some way to apply different themes/theme engines to individual programs.

Also, I don't think these gtk themes do you much good if you use a non-matching or customized theme in kde.

BTW, another problem with the different widget sets is that things like the file browser windows are completely different. The gtk2 file browser that programs like firefox/iceweasel and audacious use is not as convenient as the kde one, IMO, and unlike the themes, this can't be changed. It would be nice here too if the file browser could be built as a module, so that you could choose which one you want your entire system to use.