This functionality is entirely achievable, as it has already been implemented in similar software to BTT.
When the thumb rests on the bottom edge of the trackpad, gestures can be triggered using the index finger. This is an elegant and efficient solution. However, BTT currently lacks the ability to convert trackpad gestures into simulated mouse movements while holding down a specific mouse button.
The logic for implementing this is straightforward:
- Condition: Detect the presence of a thumb on the bottom edge of the trackpad.
- Action: Convert the movement of another finger into a mouse gesture, such as holding down the middle mouse button while moving.
For example, if I rest my right-hand thumb on the bottom edge of the trackpad and draw a "Y" shape with my index finger, it could quickly open YouTube.
This feature would significantly enhance user efficiency and add to the intuitive usability of BTT.