Your trackpad's edges are sliders.

What it does

Fringe only listens to the trackpad and never blocks a touch. A resting palm or a second finger never counts, a drag that wanders into the middle of the trackpad stops, and the top right corner stays Notification Center's.

Each edge can do something else or nothing at all, a key can be required while you drag, and the shelf widget or a shortcut pauses every gesture at once.