Good practise is to create a folder in the module and rename the folder with versionnumber. See the community commons for an example. If every module maker would do this life would be easier :)
Maybe they could update the widget xsd, and have version # as a property alongside the name, description, etc. The modeler would then display the widget version # in the Common tab.
No, would be a fine function for the modeler, file a feature request in the support portal.
Edit: In practice: If it ain't broke, don't fix it
Did anybody already found a way to tell the version of modules and widgets installed?