How to enable a GUI for root automatically when switching to root (KDE)?

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http://unix.stackexchange.com – When I want to use a GUI application as root, first I need to run xhost + as the normal user and then switch to root. Otherwise, the application won't run. This happens only in KDE, in Gnome I hadn't such a problem. How could I automate this so when I switch to root, automatically the root user has access to X? (HowTos)