Both browsers offer "prevent this page from creating additional dialogs" inside the dialog
itself, and once it is ticked every later confirm() returns false without drawing anything — so
Fix and Never a problem silently declined and read as dead buttons. Unraid swaps tabs by AJAX
without reloading, so the suppression outlived leaving the tab and only clearing history got it
back. Both now arm on the first press and act on the second, and say what the press will do
while they wait for it.