Popup hittest on bar chart should be more forgiving

### Feature Proposal

With bar charts, if one of the bars is sufficiently larger than another, the shorter bar has little or no height. This is what I would expect.

However, if I want to see what the actual number is, I need to hover over the bar in order to see the little detail popup that shows me the actual numbers. But if the bar has little to no height, it can be difficult to get this popup. In fact, if the bar has virtually no height, I found it impossible to get this popup.

It would be nice if the popup appeared even when I clicked just above the bar. This way, I could see the numbers even for a bar that has a value of zero.

### Possible Implementation

The hit testing to trigger the popup should include the area immediately above the bar.