Back in February 2015, Tim Witt released a modified Coordinate widget that also shows current map scale. I took the scale-related elements of that widget and added them to the Esri Coordinate widget released with WAB Developer Edition 2.2.
Here's a screenshot of the widget working in an app made using WAB Dev 2.2. Note that this shot is from Firefox browser (it will appear this way in Chrome as well). If IE11 is used, the scale will appear on same line as lat/long coordinates.
To install, unzip and place "Coordinate" folder in the widget folder of your WAB Dev 2.2 app after deleting the stock Esri Coordinate widget:
I strongly recommend that you DO NOT replace the stock Esri Coordinate widget in the base widget folder (\WABdev_2.2\client\stemapp\widgets), as doing so will greatly complicate general app handling (e.g. duplicating, creating) and the importing of apps from earlier versions of WAB Dev.
Let me know if any problems arise, and I will attempt to fix them.
EDIT: This widget appears to also work for WAB Dev 2.3, 2.4, and 2.5.