Tooltip based on x-value and not on euclidian distance.

[dierickxsimon]

Issue Description:

Currently, the tooltip displayed while hovering over the graph selects the closest point to the pointer based on the Euclidean distance of both the x and y values. However, this behavior can lead to inconsistencies when hovering over linked charts, as different x-values may be shown across the graphs.

Proposed Solution:

It would be beneficial to have an option to select the closest point based solely on the x-value of the pointer. This approach would ensure that linked charts consistently display the same x-value when hovered over.