| (send an-alignment-parent get-pasteboard) | 
| → (is-a?/c pasteboard%) | 
The pasteboard that this alignment is being displayed to.
| (send an-alignment-parent add-child child) → void? | 
| child : (is-a?/c alignment<%>) | 
Add the given alignment as a child after the existing child.
| (send an-alignment-parent delete-child child) → void? | 
| child : (is-a?/c alignment<%>) | 
Deletes a child from the alignments.
True if the alignment is being shown (accounting for its parent being
shown).