The idea here is to be able to interactively select and highlight data across the cross plots and log plots.

The input would be a selection via lasso or box selection on the cross plot (the blue circle) and the output would be some indication on the log trace plot which points are selected (the yellow highlights.) It also should work in reverse with selections on the log traces updating the selection on the cross plot.

This is the relevant information from the dash tutorial.
https://dash.plotly.com/interactive-graphing