Selecting vertical_span on chart

[konstantinosftw]

Question

Is there a way to select a vertical_span using the mouse on the chart and have a callback execute with start/end_times as input? I also checked the toolbox callbacks and events trying to put something together, but I couldn't figure out a way with the available interfaces (e.g. use a trendline's start/end_times as inputs for a function).

Any solution or workaround would be greatly appreciated.
Many thanks 🔥