Trigger click action with mouth gesture (smiling or opening mouth)

[1j01]

Currently the app supports dwell clicking (hovering in one spot long enough to trigger a click), but a gesture would be faster.

There is already the facemesh library included for detecting the pose of the user's face, and whilst it doesn't look like it handles eye or eyebrow movements well enough, I think detecting a smile or open mouth should work fine.
It might cause accidental clicks sometimes though when it loses proper tracking of the face, we'll have to see if that's a problem.

You should still have the option of using dwell clicking.
See #1 for support for clicking by blinking.