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
assert content != null;
		
		if ( !element.getDefn( ).isContainer( ) )
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_NOT_CONTAINER );
		ContainerSlot slot = element.getSlot( slotID );
		if ( slot == null )
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_SLOT_NOT_FOUND );
		if ( !slot.contains( content ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_CONTENT_NOT_FOUND );
		if ( !slot.canDrop( content ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_DROP_FORBIDDEN );
		
		
		if ( !content.canDrop( ) && !flag )
			throw new ContentException(
					element,
					slotID,
					content,
					ContentException.DESIGN_EXCEPTION_STRUCTURE_CHANGE_FORBIDDEN );
		
		
		if ( hasDescendents( content, slotID ) )
		{
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_HAS_DESCENDENTS );
		}