The Treeview control is the traditional way of visualizing hierarchical information in user interfaces, but in situations such as managing bookmarks in browsers, more general classifications may be more appropriate than hierarchies. We have developed a component called EulerView which is an extension of Treeview, with a similar look and feel, addressing migration, navigation and overspecificity issues amongst 2D or 3D visualisations of classifications. It has familiar characteristics, and an underlying model, based on Euler diagrams, enabling more general classifications. We found, via user testing, that users of EulerView appear to grasp a fairly accurate internal representation of Euler diagrams and that they could organise bookmarks well within in a given classification using EulerView.