Hi Geeks,
I should warn somebody who are using Ubuntu with KDE, If anyone try to
install ubuntu-sdk in KDE, the core package "kde-workspace" will be
remove by the installation process, then KDE will never show up until
"kde-workspace" reinstalled.
The reason is, the package "qtchooser" conflict with "qdbus" which is
a core package of KDE.
So the key point is, *do not install "qtchooser"*
But there's still a solution below:
1. add repository and do not try to install any packages;
2. launch "muon package manager";
3. search "ubuntu-sdk", there should be only one result;
4. click the "ubuntu-sdk" from the result list then click the
"Dependencies" below;
5. there are many packages in the list, please install them one by one
*except the first one "qt5-default"*
Test with both Kubuntu 12.04 and Kubuntu 12.10
Hope these helpful :)