You know what? Trying to fail, of sorts, on purpose is not an easy thing, I tell you

More seriously, I tried:
- put the Mini in sleeping mode w/ slider, then drop a handkerchief on the screen just after the cover image appeared,
- put the Mini in sleeping mode w/slider, then drop a handkerchief on the screen while the cover image is appearing,
- put the Mini in sleeping mode w/slider, then drop a handkerchief on the screen while the cover image is appearing and let all of them like that for 13 hours, the sleepcover setting being on but the cover remaining fully open during the test.
So far, no battery drain, just dust on the screen.
I'll try tonight to wait for the Mini to go back to sleep by itself (waking it but not touching the screen). Other than that, I don't see what else I can do. Any idea.