Grease Pencil - Preview tablet brush size / radius

Pressing F will give you a preview of the brush size. It would be nice if the same thing happened (centered on the drawing) when dragging the Radius UI control in the menu bar to set the brush radius.

Also, the draw brush is supposed to be in pixels (px) and it is nowhere near that. 500px radius draw brush should be half the height of a 1920x1080 canvas,yes/no?