[xubuntu] UID change without lose everything

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http://ubuntuforums.org – Hi, im quite new to this forum, so hello @ all my question is, that i have to change my UID, but then i do, i lose my GUI. i am using a xubuntu 12.10 so what have i to do, that i dont lose anything untill I am changing my UID? hope for quick answers regards, patrick (Hardware)