I try to catch the start and end of a selected interval. Each time i select an area with the xbox_select tool, i want to catch the start and end on x axis by a callback. I want to do it without using CDS.

I tried various things :

p.toolbar.tools[0].change(function (a,b){
console.log(a,b 
})

Nothing happens on selections.

Here is a complete Minimal Reproducible Example : https://codepen.io/BokehJS/pen/RwKeYNg

Thank you