Bug 155365 Can not set data type to "date time" when editing "Data Item"
Description: Can not set data type to "date time" when editing "Data Item" Steps to reproduce: 1. Insert a data item to the layout 2. Name it and set the expression to "a = new Date()" 3. Select the data type to date time 4. Press ok Actual result: An Birt Exception is thrown out. Expected result: No NPE thrown out
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/dialogs/DataItemBindingDialog.java
{
							setAggregateOnSelect( ALL );
						}
						else
							setAggregateOnSelect( NONE );
					}
					else if ( groupType.equals( DEUtil.TYPE_GROUP_NONE ) )
					{
						setAggregateOnSelect( NONE );
					}
				}
				if ( ExpressionUtil.hasAggregation( itemExpression.getText( ) )
						&& !itemAggregateOn.getVisible( ) )
				{
					aggregateOnLabel.setVisible( true );
					itemAggregateOn.setVisible( true );
					hiddenLabel.setVisible( true );
				}
				else if ( !ExpressionUtil.hasAggregation( itemExpression.getText( ) )
						&& itemAggregateOn.getVisible( ) )
				{
					aggregateOnLabel.setVisible( false );
					itemAggregateOn.setVisible( false );
					hiddenLabel.setVisible( false );
				}
			}
		} );
		aggregateOnLabel = new Label( composite, SWT.NONE );
		aggregateOnLabel.setText( AGGREGATE_ON );
		itemAggregateOn = new Combo( composite, SWT.BORDER | SWT.READ_ONLY );