Actually terminating a query in progress is database-specific, so
there is no EOF way to do it.
EOAdaptor's cancelFetch() should do what the method name implies.
Each database plugin includes an EOAdaptor subclass that overrides
cancelFetch() to do the database-specific mojo necessary to cancel a
fetch in progress.
You'd probably need to write your own fetchRow() loop checking at
each iteration whether to cancel the fetch. But doing so isn't as
easy in a WO app with its very long event loop compared with the
desktop environment with its short event loop. Maybe you could have
a timer running in one thread set a "cancelFetch" variable to true
while the fetch loop in a different thread could check the value of
"cancelFetch" during each iteration. But then you'd need to turn
this array of fetched dictionaries into EO's in an editing context in
the same way as using an editing context to fetch which isn't
something that I'd like to mimic.
