does Panel includes a widget that provides the feauture of selecting a value by clicking for example at a curve? The hover tool can actually display the allocated values so I think it must be possible to pickup the values an reuse them.
I am sure that I saw an example including such a widget but I’m not able to find it anymore.
Panel is responsible for the overall layout and some aspects of communication, but what’s inside a plot is up to you and your plotting library. If you have a Bokeh-based HoloViews plot, you can use HoloViews “linked streams” to provide custom interactivity like that: http://holoviews.org/user_guide/Custom_Interactivity.html