Bug 153523 OK button in parameter dialog is enabled without default value in combo-box
Description: OK button in parameter dialog is enabled without default value in combo-box Steps to reproduce: 1. New a report parameter, combo-box. 2. Click New button, input abc as value, click OK 3. Set abc as default value and close Edit Parameter dialog. 4. New a data source and dataset 5. Edit the parameter, remove abc value and import values from dataset Expected result: OK button is disabled for there is no default value. Actual result: OK button is enabled.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
if ( value == null )
					{
						value = choice.getValue( );
					}
					if ( value == null )
					{
						value = LABEL_NULL;
					}
					if ( value.equals( newValue ) )
					{
						return true;
					}
				}
			}
		}
		return false;
	}
	private void popupFormatBuilder( boolean refresh )
	{
		String type = getSelectedDataType( );
		int style;
		if ( DesignChoiceConstants.PARAM_TYPE_BOOLEAN.equals( type ) )
		{
			return;
		}
		if ( DesignChoiceConstants.PARAM_TYPE_STRING.equals( type ) )
		{
			style = FormatBuilder.STRING;
		}
		else if ( DesignChoiceConstants.PARAM_TYPE_DATETIME.equals( type ) )