The "..." menu of a row: a small icon button that opens a menu of actions fixed to the window, so the overflow
of a table or of a scroll area never cuts it. It is a DevactionUI.Dropdown with fixed on and the quiet 30px
button of a table row, and it takes the same item slots (icons, a shortcut, separators, a danger item, links
with navigate, patch or href), so the keys are the same: ↑ ↓ Home End, the first letters of a name, Esc
gives the focus back to the button.
The menu opens under the button with its end on the end of the button, above it when there is no room below,
and stays inside the window. It closes when anything scrolls or the window is resized, because it would no
longer sit under its button. The icon of the button comes in the trigger slot and its accessible name in
trigger_label (there is no visible text).