Methods, systems and computer program products for providing tree diagram graphical user interfaces having secondary expansion capabilities

Methods for displaying a set of hierarchical data and a set of non-hierarchical data on an electronic display comprise displaying at least part of the set of hierarchical data in a tree diagram that has a plurality of levels with one or more nodes present at each level, and displaying the set of non-hierarchical data in a plurality of auxiliary nodes that are provided in between levels of the tree diagram. Expansion handles may also be displayed adjacent nodes in the tree diagram. These expansion handles may be configured to expand or collapse the tree diagram at the node they are adjacent to. The expansion handles may optionally be configured to display or hide selected of the auxiliary nodes.