ReadonlyfindA window already running this catalogue id, for reuse.
Optional ReadonlyfocusReadonlyinstalledReadonlyopenAsk the host to open the applet at this address; resolves to its window id, or undefined when it did not open.
Optional ReadonlyretryReadonlysendThe runtime's recipient-checked send; false while the target is not eligible yet.
What createIntentDelivery needs from the shell.