Great work! A suggestion: to make the text searchable using Ctrl-f, please render the maps using SVG instead of canvas. For a big mind map this is indispensable.
we opted for canvas as it gives us better visualisation capabilities in the future. we could easily provide searching with canvas by overriding ctrl+f.
In general I like SVG because it doesn't try to hide the data it's displaying, unlike flash/canvas. Although I now remember seeing a hybrid div/canvas implementation which buys you best of both worlds albeit at some added complexity.