The handbook
is a graphical front end for the su command.

Introduction
Welcome to ! is a graphical front end for the su command for the K Desktop Environment. It allows you to run a program as different user by supplying the password for that user. is an unprivileged program; it uses the system's su.
has one additional feature: it can remember passwords for you. If you are using this feature, you only need to enter the password once for each command. See Password Keeping for more information on this and a security analysis.
This program is meant to be started from the command line or from .desktop files. Although it asks for the root password using a dialog, I consider it to be more of a command line <-> glue instead of a pure program.
Since kdesu is no longer installed in $(kde4-config --prefix)/bin but in kde4-config --path libexec and therefore not in your Path, you have to use $(kde4-config --path libexec)kdesu to launch kdesu.