The idea is a button that will constrain either horizontally or vertically based on the current position of a line. If the line is more horizontal, then it would add a horizontal constraint. If the line is more vertical, it would add a vertical constraint. This command could also work in 3D sketches with the X Y Z axis constraints.
There was another, somewhat similar idea posted a few years back, but never implemented.
https://forums.autodesk.com/t5/inventor-ideas/add-ctrl-behavior-to-horizontal-and-vertical-sketch-co...
