Choose a <dialog> type to show:

closedby="none"

Only closable using a specific provided mechanism, which in this case is pressing the "Close" button below.

closedby="closerequest"

Closable using the "Close" button or the Esc key.

closedby="any"

Closable using the "Close" button, the Esc key, or by clicking outside the dialog. "Light dismiss" behavior.