Paint rounded rectangle...

A command in the World menu of the Picture window, to fill a rectangle bounded by the given x and y points, and with the given radius for rounding the corners (in millimetres), with the given colour.

The coordinates x and y are to be specified as world coordinates, i.e. in the same coordinates as the latest drawing (e.g. seconds horizontally and pascals vertically) or as specified by the latest Axes... command.