child to this, packed with reference to the start of this
child is packed after any other child packed with reference to the start of this.
the Widget to be added to this
true if the new child is to be given extra space allocated to this. The extra space will be divided evenly between all children that use this option
true if space given to
extra space in pixels to put between this child and its neighbors, over and above the global amount specified by
spacing property. If