What the composer's send slot is doing. The slot is ONE button whose look, label and click
target follow this mode, so focus survives the change from Send to Stop and back.
send: the send button, as always.
stop: a stop control; the click emits StopClicked. The host decides what that stops.
stopping: a stop was asked for and has not landed yet; the slot is disabled with a spinner.
What the composer's send slot is doing. The slot is ONE button whose look, label and click target follow this mode, so focus survives the change from Send to Stop and back.
send: the send button, as always.stop: a stop control; the click emitsStopClicked. The host decides what that stops.stopping: a stop was asked for and has not landed yet; the slot is disabled with a spinner.