MBoxFCookie Xpos.w,Ypos.w,Xpos2.w,Ypos2.w[,Colour] Draw a filled box in a cookie [to specified colour]

Does the same as MBoxF but draws the filled box to the cookie of the currently
used chunky Shape. The actual value drawn to the cookie /represents/ the
currently used ink colour or the specified colour.  If the drawing mode is
set to MReMapMode or MSimpleReMapMode with the MDrawingMode command, MColourMode
will be used instead as it is illogical to try to perform remapping to the
cookie.