Bug 121864 Report element can't be deleted
Description: Report element can't be deleted Steps to reproduce: 1.Open the attached design file 2.Delete the table/parameters/dataset/datasource Expected result: The element can be deleted Actual result: They can't be deleted
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/ContentCommand.java
* Returns false if the content has ancestor behind the new position or has
	 * children before the new position.
	 * 
	 * @param content
	 *            the element to move position
	 * @param slotID
	 *            the slot that contains the element
	 * @param newPosn
	 *            the new position within the slot.
	 * @return true if the content can be moved within the slot, otherwise
	 *         false.
	 */
	private boolean canMovePosition( DesignElement content, int slotID,
			int newPosn )
	{
		if ( element instanceof ReportDesign
				&& slotID == ReportDesign.COMPONENT_SLOT )
		{
			List derived = content.getDerived( );
			ContainerSlot slot = element.getSlot( slotID );
			Iterator iter = derived.iterator( );
			while ( iter.hasNext( ) )
			{
				DesignElement child = (DesignElement) iter.next( );
				if ( slot.contains( child ) )
				{
					
					
					if ( slot.findPosn( child ) <= newPosn )
						return false;