rem: return (((c - orgc) << ZOOM_SHIFT) + (reduction >> 1)) / reduction;
add: return ((c - orgc) << ZOOM_SHIFT) / reduction;
context: CalcDisplayCoord (COORD c, COORD orgc, SIZE reduction){	/* correcting rounding error here */	return (((c - orgc) << ZOOM_SHIFT) + (reduction >> 1)) / reduction;}