1. A system for displaying and navigating hierarchically structured data, comprising: a graphical data display system for displaying a structured diagram having a plurality of nodes; a navigation system for allowing a user to launch a first viewport at a selected node within the structured diagram to view subnodes of the selected node, and to launch a second viewport embedded within the first viewport to view sub-subnodes; and a context maintenance system that maintains a visual context between each of the plurality of nodes and the subnodes within the structured diagram wherein the visual context of both the plurality of nodes and the subnodes is in a single diagram.