1. In a computer system having a display and a memory for storing items with metadata properties, a method of refining the filtering of items, the method comprising: providing a plurality of display objects on the display that each represent one or more items, wherein the plurality of display objects is populated using a first enumerator structure and wherein display objects in the plurality can be directly manipulated; filtering the items represented by the display objects based on a filter term; modifying the display objects that are provided on the display so as to represent the items that have the metadata property that corresponds to the filter term in response to the filtering of the items, wherein one or more of the modified display objects comprises a virtual folder populated by a second enumerator structure; providing additional filtering functions on the display; and in response to the modifying of the display objects, modifying the additional filtering functions provided on the display corresponding to metadata properties of the filtered items that are represented on the display.