errorMessage = ERROR_MSG_NO_DEFAULT_VALUE;
if ( !canBeNull( ) || !containValue( null, null, COLUMN_VALUE ) ) { errorMessage = ERROR_MSG_NO_DEFAULT_VALUE; }
	private void updateMessageLine( )	{		String errorMessage = validateName( );		if ( errorMessage == null )		{			if ( !isStatic( )					&& columnChooser != null					&& columnChooser.getItemCount( ) == 0 )			{				errorMessage = ERROR_MSG_NO_AVAILABLE_COLUMN;			}			else if ( defaultValue == null					&& ( PARAM_CONTROL_COMBO.equals( getSelectedControlType( ) ) || DesignChoiceConstants.PARAM_CONTROL_RADIO_BUTTON.equals( getSelectedControlType( ) ) ) )			{				// Now combo and radio must specify an default value				errorMessage = ERROR_MSG_NO_DEFAULT_VALUE;			}		}		if ( errorMessage != null )		{			errorMessageLine.setText( errorMessage );			errorMessageLine.setImage( ERROR_ICON );		}		else		{			errorMessageLine.setText( "" ); //$NON-NLS-1$			errorMessageLine.setImage( null );		}		if ( promptMessageLine != null && !promptMessageLine.isDisposed( ) )		{			if ( DesignChoiceConstants.PARAM_TYPE_DATETIME.equals( getSelectedDataType( ) ) )			{				promptMessageLine.setText( LABEL_DATETIME_PROMPT );			}			else			{				promptMessageLine.setText( "" ); //$NON-NLS-1$			}		}		updateButtons( );	}