D3 Behavior Zoom Manual Adjustment
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I'm trying to adjust the zoom level manually in a fairly simple d3 visualization I'm developing. See: http://jsfiddle.net/TXPcM/

After zooming and panning around (use shift+click to zoom out) press the "Default Zoom" button then try to pan around again. You'll notice a jarring shift as it "resets" to the state prior to the button press.

The code is a bit of a prototype and fairly long winded - but look for the applyZoom function. The intention here was to re-apply the zoom behaviour and thus, hopefully clear out any cached values it might be using. Doesn't seem to work. Suggestions?