From Larry's main widget page...
Here is my entire application, which includes my Acme Widget. The Acme Widget is invisible, but adds key functionality to the basic Web AppBuilder viewer and modifies the appearance and/or behavior of several Esri Widgets (without editing the Widgets themselves).
This is a new link for downloading a sample of the full sample app and documentation by Larry Stout (re-posted with Larry's permission 2/18/2017). The download link on his main description page Larrys Custom WAB Widgets and More and the individual widget pages is no longer accessible. See the my comment on any of these pages, or on the Web AppBuilder Developer Edition - Customization Resource List (updated 2/18/2017) for a the updated links for all hist widgets on this page.
NOTE: These widgets were written for an earlier version of WAB developer edition so may not work without modifications with current developer edition versions. Larry has changed jobs and is not working/updating these. They are as-is, with no direct support from Larry, but others in the forums might be able to respond to questions. If anyone does update, please share so others can benefit. Thanks.