Comment 53 for bug 1366421

Hmm, doesn't look like it's working as intended. Auto-hide on key-press is interfering. I missed to blacklist the keycodes for tablet-mode detection, will do that. For the time being please disable Preference->Auto-show->"Hide when typing on a physical keyboard".

Then, there are no incoming key-presses 70 or 71, just 200 and 201. Please try 200/201 in preferences please, or more likely 201/200. 200 is touchpad on, which I believe means tablet-mode off.

>Meanwhile, I'm wondering if Onboard uses hotkeys at all for tablet-mode
> switching, or if any of the two other approaches have started working.
Nope, they haven't. No SW_TABLET_MODE or sysfs paths, as expected.

One more time onboard -ddebug and going tablet and back would be helpful, even if it appears to work now.
There should be entries
 AutoShow can_show_keyboard: locks=[] tablet_mode=True
and
 AutoShow can_show_keyboard: locks=[] tablet_mode=False
if it does.