Rythmbox library set to: multiple locations and no way to edit/change

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http://askubuntu.com – I previously set Rythmbox to include a few different locations. Now following changes to my directory structure, I'd like to reflect these changes in Rythmbox. But when I go to "Library Location" I see "Multiple locations Set" and I can only add to the list; no way to edit/remove. I Googled this problem and the only relevant results I get date back to 2006, probably referring to a previous version of Rythmbox" and specifying components/locations that I can't find on my system. Gave a look at the documentation.... kind of minimal. Any clues ? Thanks in advance, Pierre Ubuntu 12.04 Rythmbo (HowTos)