Device: LG G4 (Android 5.1 ) Build: Nightly 55.0a1 (2017-04-10); Steps to reproduce: 1. Open a website that supports the standalone display (e.g. twitter.com) 2. Bookmark the website. 3. In a different tab, go to about:home and open the Bookmarks panel. 4. Long tap the bookmark made at Step 1. Add the app to the home screen. 5. Open the home screen shortcut. 6. Repeat Steps 3-6 by using the website's History panel entry. Expected result: Shortcuts added from bookmarks/history to the home screen should open the app in standalone mode. Same as it does when adding the shortcut from the browser's custom menu. Actual result: If the website is not loaded in the same tab, when you tap the URL bar to open about:home, adding the shortcut from the history/bookmark tab doesn't install the web app. Notes: If the website is loaded in the same tab where you open the bookmarks/history panel, it will be installed correctly.

This may be tricky, from "Add to Homescreen" on the page overflow menu we have the loaded page in context and know whether the page has a manifest or not. From the bookmark / history panel we do not have a loaded page. Would need to load the page in the background for this to work which seems problematic. The ideal solution for this probably needs a bit more thought and some input from design / product

[triage] shouldn't be a blocker: P2

Not blocking

No longer a valid bug since Bug 1393672.