Draw multiple slider vertical lines in the main plotting area.

[alexk11]

Hello,
First of all PlotJuggler is an incredibly useful tool, thanks a lot for developing it.

I would like to be able to draw multiple slider lines on the main screen. When the slider moved to a new position, then the vertical line and the value mark at the previous spot should persist.
Another way to achieve that would be to intercept a mouse click event, get the point clicked, and to draw a vertical line there.
Would it be possible?