Plot value not restored correctly when interacting with multiple pointers

[mootari]

If the mouse is within the radius of multiple pointers and moves outside of one pointer's max radius, then the plot value will be set to null instead of according to the remaining active pointer.

Example (notebook):

viewof value = Plot.plot({
  marks: [
    Plot.frame(),
    Plot.rect(["foo"], Plot.pointerY({y: d => d, maxRadius: Infinity, fill: "orange"})),
    Plot.dot([{y: "foo"}], {y: "y", tip: true})
  ],
})

Steps:

1. Move the mouse into the frame on either the left or right side so that value reads "foo".
2. Move the mouse towards the dot until the tip appears; observe that value reads {y: "foo"}.
3. Within the frame, move the mouse away from the dot until the tip disappears; observe that value reads null instead of "foo".

Demo:

2026-05-07.at.1.34.08.-.Blue.Horse.mp4

[Fil]

related? #2382

[mootari]

I'm afraid not, the problem also exists in dev regardless of the pool setting. I've added another example to the notebook using the unreleased version. The only difference is that with pooling enabled only the latter pointer will override the prior pointer's value to null.

For reference:

PlotDev.plot({
  margin: 30,
  width: 150 + 60,
  marks: [
    PlotDev.dot([{y: "foo", x: 0}], {x: "x", y: "y", tip: {maxRadius: 100, pool}, r: 10, fill: "blue"}),
    PlotDev.dot([{y: "foo", x: 1}], {x: "x", y: "y", tip: {maxRadius: 100, pool}, r: 10, fill: "red"}),
  ],
})