How do I adjust the margin for the line numbers in gEdit?

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http://askubuntu.com – Recently I was able to increase the left margin between code and line numbers in Gedit (Gnome-text-editor) in Ubuntu 12.10. I don't recall how I achieved this, neither do I recall how Gedit reverted to the classical margin which is very tight for me. See screenshot: Does anyone know how I can increase left margin in Gedit 3.6.1? Thanks (HowTos)