Have anyone created a custom property type that supports multiple select? Normally I would use a standard category structure for this purpose, but in this case there are two reasons why this is not sufficient: 1) The categories are already in use for other purposes (btw: is it possible to have more than one set of categories? If so -how?) 2) The available values are quite many, so an aphabetized drop-down, or an expandable tree-structure would be more suitable. Anyone out there that may supply some inspiration -or even a solution to this problem?