There is a problem with showing tooltip for certain point on the scatter series when marker is bigger than stardard (by increasing radius or lineWidth). The same with custom marker. Hoovering diamond/line should show tooltip for this point - not for column.
The rationale is that for scatter plots, the marker itself acts as a mouse
tracker, to increase performance. While for columns and lines, there is a
separate tracker object above the graphic to increase sensibility.
Duplicate of #861