There is no reason to have the same app-tabs across Windows and that would make it not attached to the window, so the answer would be no, if that is what you said. You can certainly have app-tabs on more than one window.

I don't know why a number of people don't see them across sessions and I can only assume that they are not closing all their windows at once by exiting Firefox.

Because you can open another page from the same site in an app-tab, I end up starting them fresh every once in awhile. Which is what you are doing because you don;'t see them being saved. But I would never rely on them lasting forever anyway so I have them in a folder where I can open the entire folder into tabs, and then using Multiple Tab Handler extension pin all of the selected tabs at once.

Check out how you are closing Firefox and how to restore previous session then previous windows.

• app-tabs https://support.mozilla.com/en-US/questions/837562
• app-tabs https://support.mozilla.com/en-US/questions/840004
• app-tabs improperly closing use History to restore - https://support.mozilla.com/questions/840583

App (pinned) tabs and Tab Groups (Panorama) are stored as part of the session data in the file sessionstore.js in the Firefox profile folder. So do not remove the history via Delete browsing, search and download history on Firefox when you exit Firefox.

• http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox
• http://kb.mozillazine.org/sessionstore.js
• http://kb.mozillazine.org/Session_Restore

Each window can have its own set of App Tabs.