Bug 151959 inappropriate screen operation
steps to reproduce: - create a report - add a grid item (3x3) - switch to Outline view - expand the grid item to see its rows and cells - select the grid item, and drag it into any of its own cell expected behavior: - is it an invalid screen operation? if it is, it should be banned actual behavior: - the grid item was disappeared surprisingly
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
{
			Iterator iter = getSlot( i ).iterator( );
			while ( iter.hasNext( ) )
			{
				list.addAll( ( (DesignElement) iter.next( ) )
						.validateWithContents( module ) );
			}
		}
		return list;
	}
	/**
	 * Validates only this element without its contents, and return error list.
	 * The derived class should override this method to define specific
	 * validation rules.
	 * 
	 * @param module
	 *            the module
	 * @return the list of the errors found in validation, each of which is the
	 *         <code>SemanticException</code> object.
	 */
	public List validate( Module module )
	{
		errors = new ArrayList( );
		
		errors.addAll( UnsupportedElementValidator.getInstance( ).validate(
				module, this ) );