Apple trackpads, both external and built-in, have one fantastic gesture which is not enabled by default:
3 finger drag
https://support.apple.com/en-us/HT204609
This allows you to easily grab windows and files without needing to hold down the trackpad like a mouse button. For GUI designers it means quickly resizing and positioning controls, like Tom Cruise in Minority Report 😎
Carpe Diem Systems Ltd. 