PointerY falls back to nearest X/Y outside of frame

[mootari]

When the cursor is moved outside of the frame area, PointerY will no longer match by closest Y, instead matching the closest point b X/Y distance.

This is problematic when hovering axis labels, as the tooltip may no longer line up with the axis label.

Example:

Plot.plot({
  height: 100,
  marks: [
    Plot.frame(),
    Plot.dot([1,2,1], {x: d => d, y: (d, i) => i, tip: {pointer: "y"}}),
  ],
})

2026-06-22.at.12.24.50.-.Blush.Wallaby.mp4

[mootari]

The behavior is governed by the facet handling in

plot/src/interactions/pointer.js

Lines 143 to 144 in 356f579

	const kpx = xp < dimensions.marginLeft || xp > dimensions.width - dimensions.marginRight ? 1 : kx;
	const kpy = yp < dimensions.marginTop || yp > dimensions.height - dimensions.marginBottom ? 1 : ky;

A workaround is to replace margins with insets, e.g.:

Plot.plot({
  height: 100,
  marginLeft: 0,
  marginRight: 0,
  insetLeft: 40,
  insetRight: 20,
  marks: [
    Plot.frame({insetLeft: 40, insetRight: 20}),
    Plot.axisY({dx: 40}),
    Plot.dot([1,2,1], {x: d => d, y: (d, i) => i, tip: {pointer: "y"}}),
  ],
})

[Fil]

This works as expected — but (as the comment outlines) it was designed with facet handling in mind: when outside the frame, we want to select the closest point from the closest facet (which is why we use the normal "xy" euclidian distance). In the case where there are no facets, the behavior you want might be preferable. I don't have a concrete suggestion to make it work "intuitively" in all cases without actually implementing a search in two steps (facet then data point).