It functions in this way: When loading the page, the login popup pops up. Then is deactivated after 1/2 second or so.
This is the ONLY login-popup-blocker who actually succeeds in this. Thank you.
In the next iteration I hope the popup-window will be blocked even before it appears.
Good work so far.
Note: I have tried and confirmed this at reddit.com, no other places so far. So lucky login-popup hunting!