Feature suggestion: math in guide angle box

It would be a neat little feature if text entry in the Angle box for a guide could do math, e.g. “90-12” to match my 12° italic angle. (The x: and y: boxes already do this.)

Sort of related: would it be useful if the guide, when rotated with the mouse, also snapped to the italic angle in the same way it snaps to vertical and horizontal?

i second that, wanted to request the exact same thing.