Elastic Windows' origin goes back as far as Nassi-Shneiderman diagrams  (Figure ). Nassi-Shneiderman diagrams depict the program structure in flow charts by appropriate tilings of rectangular boxes. Each programming construct such as if, while, for, etc. has a corresponding box representation. A program sequence is represented by vertically stacked boxes for each program segment. Following on this idea, the treemap concept was developed by Shneiderman  and implemented by Johnson  (Figure ). Treemaps are novel visualization methods that map hierarchically structured data to nested boxes in a space-filling manner, where users can interactively specify presentation attributes of both structure and content of the data. Application of the space-filling tiling of the screen space to present personal information originates from the work by Plaisant and Shneiderman  (Figure ). The Elastic Windows approach extends this work by providing arbitrarily deep nested hierarchical windows, where users can operate on windows at any level of the hierarchy. The Elastic Windows approach also facilitates multi-window operations by applying window operations on group of windows at any level of the hierarchy. The elastic sheet metaphor is exploited for dynamics of the layout, where windows stretch and shrink like an elastic material allowing more information to be presented in a smaller screen space.