Mouse events should work for near-zero bar values

On a bar chart, some values are occasionally near zero:


Mouse events and popups should still work for such bars. A possible solution is to increase sensitive area for such bars vertically.

Start by locating the bar-chart rendering and mouse-event or popup handling, then reproduce the issue with values near zero. Adjust the sensitive area so these bars remain interactive, and verify that mouse events and popups work for them without changing larger bars.

Written by the indexing model from the issue text.