InvertOval
InvertOval Invert all pixels in an oval
#include <Quickdraw.h> Quickdraw
void InvertOval(theRect );
Rect *theRect ; rectangle defining oval's position and size
InvertOval inverts all pixels in an oval positioned just inside the specified
rectangle. All black pixels are set to white and vice versa.
theRect is the address of an 8-byte Rect structure, in local coordinates.
Returns: none

Notes: For "old model" color, the output result of all Invertxxx functions
depends upon the device being used.
InvertOval doesn't change the pen position.
As with all Quickdraw drawing, the output is clipped to the intersection of
the current GrafPort's bitMap boundary rectangle, the port rectangle,
clipping region, and visible region.