Add synchronized position indicator between minimap and main timeline

[yurishkuro]

In Grafana when you mouse-over one graph, a vertical bar shows the respective position in all other graphs. We should do the same in the trace view, because sometimes I want to zoom in onto some small spans on the main timeline, but I don't know where they are in the minimap.

[tiffon]

Thanks for filing this!

Not sure if this will help in the short term, but it might be useful to use the heading row above the trace timeline, the "Service & Operation" row. The portion above the span bars can be used to manage the zoom.

[yurishkuro]

Why do we only show the red line when the mouse is over the timeline? Why not have it always follow the mouse, even on top of the Gantt chart? Sometimes it's a useful indicator when I want to see how two spans are aligned against each other, or, as in the ticket, do a precise zoom.