(In reply to Jane Wolf from comment #2)
Thanks for sharing this, my questions center around why we're showing a paste option on a button. A button is an action that a user wants to take, typically to go somewhere, so it seems like an unexpected behavior. Can you outline what the goals of the paste action are
The goal is to allow a website to ask the user for permission to paste their clipboard content to that website. That already requires user interaction (e.g. clicking somewhere on the website).
The new "Paste" button can be seen as a stripped down version of the right-click menu, which also includes a "Paste" menu item.
, as well as what type of feedback you're looking for from UX?
Just a sanity check, a different viewpoint than the software-developer's one; to ensure the UX is pleasing. Please see also bug 1774163 and comment there, in case you've thoughts about that topic.