Bug 202891 NPE throws out when click on data item in layout[0001]
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/dialogs/BindingDialogHelper.java
{
						if ( DATA_TYPE_CHOICES[i].getName( )
								.equals( getBinding( ).getDataType( ) ) )
						{
							setTypeSelect( DATA_TYPE_CHOICES[i].getDisplayName( ) );
							break;
						}
					}
					setDataFieldExpression( getBinding( ).getExpression( ) );
				}
			}
			else
			{
				setTypeSelect( dataTypes[0] );
				this.newBinding = StructureFactory.newComputedColumn( getBindingHolder( ),
						isAggregate( ) ? DEFAULT_AGGREGATION_NAME
								: DEFAULT_ITEM_NAME );
				setName( this.newBinding.getName( ) );
			}
		}
		else
		{
			if ( isRef )
			{
				int i = 0;
				for ( Iterator iterator = getBindingHolder( ).getDataBindingReference( )
						.getColumnBindings( )
						.iterator( ); iterator.hasNext( ); )
				{
					ComputedColumnHandle computedColumn = (ComputedColumnHandle) iterator.next( );