Making it more clear how Shear works

The Shear operator's description in the manual all talk about how the Shear operator moves vertices. For example:

The magnitude of the Shear transform applied to the selected elements is directly proportional to the distance from the horizontal axis. i.e. the further from the axis, the greater the movement.

This isn't how most people use it, and it isn't how it's perceived when used inside Blender. When Shear is used on a single edge loop, and the Shear value is at 1.0, the edge loop "rotates" exactly 45 degrees (or at least, that's how it looks like for the user).

The size of the sheared object, the shape of the edge loop, and the edge loop's relative position to the transform pivot point are all irrelevant - they might change the final position of the vertices, but when an edge loop is Sheared at value 1.0, the edge loop will (in many cases) seem to rotate 45 degrees.

The relation between Shear value and the angle of the visual rotation is through tangent. Tan(45) = 1.0 ; to rotate an edge loop by 45 dgrees (or cause a movement which produces visual rotation similar to 45 degrees), the user needs to use a Shear value of 1.0. Similarly, Tan(30) is about 0.577, so Shear value of 0.577 causes a visual rotation of about 30 degrees.

Since there is already a clear mathematically defined connection between the angle and the Shear value, it should be relatively simple to add an option which lets the users define the Shear with a rotation, instead of with a value. There should be some limits, of course, to prevent a 90 degree rotation.

Even if that isn't done, the page for Shear in the Blender Manual doesn't describe the relation between Shear, shear value, and what the rotation of a horizontal or vertical edge loop seems to be after the transformation.

Image of Shear below. Even though Shear moves vertices, visually, using Shear on horizontal edge loops seems to cause them to rotate. In this case, Shear at value 1.0 causes a "rotation" of 45 degrees.