Brew MP 1.0.2
This function is used get the minimum union area in pixels^2.
This area is used when attempting to merge together invalidates. If the area
of the union of both invalidation rectangles is less than or equal to the min
union area, it will use the union directly and will not attempt to use the
threshold union calculation.
This area is used to ensure that two invalidation rects are significantly
apart from each other before attempting to keep track of them separately.
Pointer to the IWidget interface object.
Will hold the return value of the property