4.2.7.3. Top, Middle, and Bottom Align
From Dia
The align top, middle, and bottom are used to align objects arranged horizontally on the canvas. The align top aligns the selected objects to the top edge of the upper-most object. Similarly, the align bottom aligns the selected objects to the bottom edge of the lowest object. Align middle aligns the middle of each object to the mid-point between the extreme top and extreme bottom edge of all selected objects. Examples of align top, middle, and bottom are shown below.
