Base class for box containers. Arranges child controls vertically or horizontally, and rearranges the controls automatically when their minimum size changes. Adds a control to the box as a spacer. If [code]true[/code], [i]begin[/i] will insert the spacer control in front of other children. The alignment of the container's children (must be one of ALIGN_BEGIN, ALIGN_CENTER, or ALIGN_END). Aligns children with the beginning of the container. Aligns children with the center of the container. Aligns children with the end of the container.