Re: Note 5 menu button
Just ran into this issue too. I can confirm long press of the back button does trigger the "hardware menu button" but that on some apps (or devices?), long-pressing the back button just closes the app or goes back to a previous screen. I made an account here to share a workaround:
In device Settings: Personal > Lock screen and security > Other security settings > Pin windows - turn this feature on. Now, open the app in question, and press the recent apps button and drag the current app up a bit, now that app pinning is enabled, there should be a thumb tack icon on bottom right of the app "card" - tap it to pin the app. You'll be prompted; tap START. The app is now pinned, and the back button will not be allowed to back out of the app (if it still page transitions, this method may not work for you). Long press the back button for the menu. Long press the recent app button to unpin the app.
Cheers.