First of all: Not sure if this feature should appear - the checklist does not contain every hint as to do this.

Ok, here's the problem:

1.) Draw a non-closed planar figure like lines or paths with the measurement tool
2.) Select the Statistics view
3.) Wait for the calculation to be finished and zoom inside the histogram

PROBLEM: Now here aren't any tooltips, only when you zoomed out as possible and the histogram is centred and displayed in it's full beauty :-P