> Why OutputArea.auto_scroll_threshold instead of that.auto_scroll_threshold?

Because `that.auto_scroll_threshold` is `undefined`, Yes I was astonished by it also. I could make it a prototype, but then it becames difficult to change it on the all notebook at once.

> In fact, this line shouldn't change at all - the threshold > 0 check should just be placed inside _should_scroll,

agreed for the `> 0` ,but the `that._should_scroll(OutputArea.auto_scroll_treshold)` is necessary otherwise it will always auto-scroll at the point where the cell is long enough...

> Also, it's spelled "threshold", not "treshold"
Damnit !, thanks.