Selection Interval does not work for line plots

[lucharo]

Hi, I've noticed that selection interval work well for scatter (point) plots but it makes the lines in line plots transparent (see video attached). I think it would be desirable if selection interval worked for line plots as well, I understand the "selection" in line plot is per line rather than per x/y interval.
Apologies in advance if this is a vega-lite request

relevant docs:

• https://altair-viz.github.io/altair-tutorial/notebooks/06-Selections.html
• https://altair-viz.github.io/user_guide/generated/api/altair.selection_interval.html

Have you considered any alternative solutions?

Overlaying the line plot with a point plot but the lines are still blurred

Screen.Recording.2025-03-31.at.16.56.47.mov