APG 3.0a1: Is this an undocumented (nice) new feature?
By dropping it on the main window several times, it is now possible to load a sole image to mimic a multiple source in a single project. Forcing it (i.e. them all) into the panorama before detection is quietly accepted by APG and thus subsequent detection is seemingly performed. A viable "panorama" appears in the panorama window. Thanks to Kolor for this nice improvement although I have detected some minor bugs associated with this novel function that I may report on the appropriate channel.
I had missed this feature before for doing some studies with the help of specially fabricated "synthetic" source images.