This is a way of working with GUIs that provide access to complex data, and it seems to scale really quite well indeed. You do it by separating the code to implement the Model (your underlying data is, say, an updatable list or a read-only tree) from the View (how your data looks when drawn on the screen) and the Controller (how your model responds to updates to the view) though often the view and controller are joined together.
Some features of Tk operate in this way; notably the -variable option to entry, the -textvariable option to label, button et al, and the -listvariable option to listbox.