Popasl creates asynchronous popups. Requesters are opened in a
seperately spawned task and don't disturb the rest of the
application. You can ask for the state of a requester by
querying the MUIA_Popasl_Active attribute. It will return
TRUE when the requester is currently open, FALSE otherwise.
Common use for this attribute is to prevent an application
from being terminated while a requester is open. If you
try to dispose the popasl object with a currently open
requester, MUI will freeze your task as long as the requester
stays there.