Deleting or detaching a disk, deleting a network card, forcing a VM off,
reverting or deleting a snapshot, stopping or deleting a pool, a
network, an interface, a filter or a secret, and the other actions that
ask first opened the browser's yes/no box (confirm()), and the ISO
upload told its mistakes in the browser's alert().
One dialog in the base page now asks for all of them: its title and
confirming button carry the button's own words, its body the button's
question, the confirming button red for a destructive action. Confirmed,
the button is clicked again, so its form sends what it did before. A
button inside another dialog (the flavors) hides that one while asking
and shows it again after; Cancel gives the focus back, and the
confirming button acts once. The ISO upload's mistakes show in its
dialog's error box, announced.
