In current version this scenario is impossible:
1) load data
2) zoom in
3) enable tooltip (whatever that means programmatically - now basically deleting the charts element and constructing new, then zooming in with setExtremes)
4) zoom out to the full range previously loaded (that is what's now impossible)

In my current project I run into this scenario quite often.

And, by the way, the Highcharts library is really good, tank you for the job well done!