A 2nd thread – I would not have thought that would work (and obviously I would have been wrong…) – I’ve used the Hook technique to automatically handle a dialog, not in a TWAIN context.
I would love to see the TWAIN standard (1) require that sources not display *any* error dialogs until the app has had a chance to negotiate, and (2) add a capability that suppresses all pop-ups. It actually wouldn’t be hard for most driver writers to code – basically an “if !bSuppressDialogs” around each MessageBox call. One alternative would be a MSG_OPENDSQUIETLY – which would mean “open the DS with absolutely *no* user interaction allowed”. A failure from that would be much more useful than e.g. CAP_DEVICEONLINE as it is currently implemented.