vncserver on display 0 instead of 1?

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http://www.linuxquestions.org – Hi guys, I somehow managed quite some time a go to setup a system and connect to the active display with vnc of an unmanaged system - it's a 'display/presentation' box running Debian with Gnome. I guess that I've used the standard remote desktop option but I can't remember and cannot find any other traces. Now, I want to setup similar system with a RPI with LXDE but with tightvncserver, I cannot set it to display :0 since some files are locked. The ability to see what is actually displayed to the connected screen is crucial since it's unmanaged and difficult to reach and preferably remotely (HowTos)