Bug 123207 PropertyHandle items cannot be moved down
Use the property handle to move down the item. It seems not work.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/activity/AbstractElementCommand.java
*            the old position
	 * @param newPosn
	 *            the new position
	 * @param size
	 *            the list size
	 * @return the adjusted new position.
	 */
	static protected int checkAndAdjustPosition( int oldPosn, int newPosn,
			int size )
	{
		if ( newPosn < 0 )
			newPosn = 0;
		if ( newPosn > size - 1 )
			newPosn = size;
		if ( oldPosn < 0 || oldPosn > size )
			throw new IndexOutOfBoundsException(
					"From: " + oldPosn + ", List Size: " + size ); 
		if ( newPosn < 0 || newPosn > size )
			throw new IndexOutOfBoundsException(
					"To: " + newPosn + ", List Size: " + size ); 
		if ( oldPosn == newPosn || oldPosn + 1 == newPosn )
			return oldPosn;
		
		
		if ( oldPosn < newPosn )
			return newPosn - 1;
		return newPosn;
	}
}