javascript layer siblingAbove, siblingBelow

Return a reference to the positionable element whose stacking z-order is above or below the current element, but only within the context of the shared parentLayer. If the current element is the highest element, the siblingAbove property returns null. To widen the examination of next higher or lower elements to a document-wide context, see above and below. To adjust the stacking order with respect to specific objects, see the moveAbove( ) and moveBelow( ) methods.