24. The computer-implemented method of claim 22 , comprising modifying a visual characteristic for graphical tiles representing child nodes when a graphical tile for a parent node is selected.
24. The computer-implemented method of claim 22 , comprising modifying a visual characteristic for graphical tiles representing child nodes when a graphical tile for a parent node is selected. 25. The computer-implemented method of claim 24 , comprising generating a border around a first set of graphical tiles when presented in a top layer.