Notice the icon in the message box. VA Smalltalk uses the type: parameter of the id:constName:type:string:translatable: method to determine which icon to display. You evaluated this method in the NLS Workspace - Indexed Messages window to create a message. Some available choices for the type: parameter are $i, $w, and $e. The corresponding icons for these choices are:

To display a different icon, change the value specified for the type: parameter.