AFAIK that isn't possible. You can make a Bookmark or Homepage location.

You might be better off asking your question here; https://support.microsoft.com

http://answers.microsoft.com/en-US/windows/forum/windows_10

Do you mean a separate window instead of a tab in the same window? Or something completely and totally separate from the user's current browser?

For tips on triggering Firefox to open a separate window, check out this page:

https://www.jeffersonscher.com/res/popit.html

A batch program (Windows) can be set up to open a specific program to a specific file.

If you can accept to use a desktop shortcut then you can simply add the URL to the target line in a copy of this shortcut.

• https://developer.mozilla.org/en-US/Command_Line_Options