private int[][] GetRectangles()
{
int[][] intRects = new int[rectangles.Count][];
for (int i = 0; i < rectangles.Count; i++)
{
ExcelRectangle rect = rectangles[i];
intRects[i] = new int[] {rect.RowFirst, rect.RowLast,
rect.ColumnFirst, rect.ColumnLast};
}
return intRects;
}