I just installed KDE and I like it very much and have themed it up a bit.
Like all that lightblue design, but how do I change the theme for GNOME applications like nautilus or marlin? and also how do I change the gray color of kmess and Chromium and many other apps?
I installed kde with this command
sudo apt-get install kde-full
Oxygen widget theme for GTK+/GTK3-based applications
The Kubuntu /1/ is using the gtk2-engines-oxygen /2/ and the gtk3-engines-oxygen /3/ as part of the desktop.
If you don't want to use the Kubuntu desktop you could install the gtk2/gtk3 engines.
Installing KDE
By the Ubuntu community wiki - Installing KDE /4/:
If you choose to not install kubuntu-desktop, then you can still get
all the Kubuntu-specific tweaks by installing the
kubuntu-default-settings package.
More
Other options:
PPA package search: https://launchpad.net/ubuntu/+ppas
=> A PPA: https://launchpad.net/~hrvojes/+archive/kde-goodies
Links
