After more researching, I've found that alternative disposition of rectangles from left to right and then in next row from right to left has some lacks - while grouping in revising order groups are different than afterward row calculation as groups are alternatively reversed and therefore dimension in afterward row calculation may jump in from different group (next one) - this causes that method can't be reliable and therefore I've returned my code in previous state - sorting and disposition is going only from left to right by rows and height of boxes are growing constantly... My code revised now - look in my last posted colored code tag...