For me, particularly, it would be extremely helpful to have crosshair on the Range Volume Profile graphs. Would help, e.g., for placing orders at low volume nodes, or drawing horizontal lines there. Currently I'm "eyeballing" these levels, and crosshair would be great to get more precision.
I have seen similar requests for extending crosshairs on other side columns, like DOM, etc. Seems it would be a nice option to add to numerous columns, especially those with graphical displays.