Popup window for browser button currently loses it’s state when closed.
Reasoning: Browser logic automatically closes popup when it looses focus, this most commonly include clicking outside of popup, whether accidentally, or when trying to switch to another tab.
less commonly: I use a clipboard manager, and some times I want to paste a previously copied URL or username, but once I do that - the content is lost.
It is completely understandable that state preservation is probably a complex solution, but it would make saving new logins and editing existing records frustration free.
2nd best solution: Add an option to automatic popup window when editing, better yet, open in a tab.