Bug 153405 Null parameter value is inconsistent between designer and preview
Description: Null parameter value is inconsistent between designer and preview Steps to reproduce: 1. New a report parameter, list-box, tick AllowNull. 2. Click New button, click OK without input anything. 3. Drag the parameter to Layout and preview Actual result: After step2, display text is "Null" and value is empty. However, when preview, the display text is "Null Value". Expected result: Display text and value should be consistent between Edit Parameter Dialog in Layout and Parameter dialog during preview.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
clearArea( valueArea );
						switchToList( );
					}
				}
				else if ( DesignChoiceConstants.PARAM_CONTROL_TEXT_BOX.equals( type ) )
				{
					clearArea( valueArea );
					switchToText( );
				}
				valueArea.layout( );
				initValueArea( );
				lastControlType = type;
			}
		}
		updateCheckBoxArea( );
		updateMessageLine( );
		boolean radioEnable = false;
		if ( PARAM_CONTROL_COMBO.equals( getSelectedControlType( ) )
				|| PARAM_CONTROL_LIST.equals( getSelectedControlType( ) ) )
		{
			radioEnable = true;
		}
		if ( radioEnable != staticRadio.isEnabled( ) )
		{
			staticRadio.setEnabled( radioEnable );
			dynamicRadio.setEnabled( radioEnable );
		}
	}
	private void switchParamterType( )
	{