Hover tooltip minimal target size

[adriengcql]

When the markers in a plot are small, it is not always easy to aim at a point to get the tooltip.

It would be great if the area around the marker also triggered the tooltip display.

A workaround is to increase the marker size, but this tends to make the plot less readable.

[hoxbro]

I don't think an API in Bokeh makes this possible. @mattpap can you confirm this? And if is not possible, is there an open feature request around this? The only one I could find was bokeh/bokeh#7338.

[mattpap]

This bokeh/bokeh#6806 is the relevant issue. Currently every glyph/annotation/etc. manages hit threshold on its own, if at all. Luckily marker/scatter glyph supports hit_dilation property (default 1px), so this should help with this particular issue.