Bug 166015 Refactor designer actions to eclipse command framework
Eclipse command framework provide a more explicit way to manage UI actions contributions, we can take it's advantage to make our actions code more clean and maintainable.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/views/actions/InsertAction.java
this.slotHandle = getDefaultSlotHandle( );
		}
	}
	/**
	 * Gets the default slot handle to insert
	 * 
	 * @return Returns the default slot handle to insert
	 */
	private SlotHandle getDefaultSlotHandle( )
	{
		Object obj = getSelection( );
 
		if(obj instanceof SlotHandle)
		{
			return (SlotHandle)obj;
		}
		DesignElementHandle handle = (DesignElementHandle) obj;
		if ( position == CURRENT )
		{
			int slotId = DEUtil.getDefaultSlotID( handle );
			if ( slotId != -1 )
			{
				return handle.getSlot( slotId );
			}
		}
		return handle.getContainerSlotHandle( );
	}
	/*
	 * (non-Javadoc)
	 *