A Behavior to make the UWP Hub control adjust the width of each HubSection to fill the Hub width. It will also snap in place when swiped. When Windows 10 Mobile came out, the Hub control functionality was quite different than the Windows Phone 8.1 control. There were two main differencies.
The HubSections no longer fit the width of the screen by default
The HubSections no longer snapped in place when swiped
The intention of this behavior is to give the above functionality to the UWP Hub control when running on a mobile device.