Mozilla is adding a native Windows 10 Share experience to Firefox 64. This allows users to share web sites using a variety of applications that are installed in Windows 10.
Similar to how mobile browsers are able to utilize the sharing controls of the mobile operating system, Windows 10 exposes its data transfer controls so that applications can share information with other installed programs.
Starting in Firefox 64, and available now in Firefox Nightly, users can click on the ... menu in the address and then click on the Share button as shown below.
This will open up the native Windows 10 Share dialog box that allows you to share the URL with other installed applications.
By default, you will be able to share the url using OneNote, Twitter, Mail, Skype, or Messenger if its installed. You can also set it as a Cortana Reminder or simply copy the link. This is a nice feature to have in desktop browsers as it is so heavily used in the mobile counterparts.
Mozilla also recently added the ability to display browser notifications directly in the Windows 10 action center to Firefox 64. This further shows that Mozilla aims to integrated Firefox into the Windows 10 operating system rather than just being another installed app.