Haven't tested it yet but looks good in general except for one thing:
Deleted entries aren't removed from AutoTypeMatchModel.
This leads to a crash if you activate global auto-type, delete an entry that appears in the select dialog and then click on that entry in the dialog.

You could do this by connecting to the entries' destroyed() signal.

Also tests would be nice :)

Thanks for the comments. I'll handle these in the next couple of weeks (a bit busy with other things recently).
:)

Bug fixed! And the other minor stuff.

I haven't added tests since I'm not sure how to trigger global autotype in the gui test code (with focus on what window?) or generally how to verify that what gets displayed is correct upon updates of the entries. It looks like the setup for the regular tests and the gui tests are subtly different - I tried to trigger global autotype with two matches in the non-gui tests but got a failure saying that "Cannot create a QWidget when no GUI is being used".

I've mostly been learning by example - prior to this I haven't ever used the qt stuff nor done any gui programming in c++ - so it's tricky for me without an existing example of autotype in the gui tests. I did play around with the gui a bit manually though. Things seem to work now with updating and deleting of entries. In the case where you change the sequence or the association, it doesn't update, but instead uses whatever it was at the time of autotype key press. But I guess that's okay.

Ping. I think this is done here, but let me know if you disagree. There's not a new automated gui test as per the previous comment, but otherwise I do think things work from testing by hand. If there's something simple and quick I can do that would help you out here I'm happy to do so, otherwise feel free to do whatever you like with this code submission.