I think it follows from Fitts' Law or rather is its reverse: If the cursor is outside an area, the bigger and closer this area is the easier it is to purposefu

I think it follows from Fitts' Law or rather is its reverse: If the cursor is outside an area, the bigger and closer this area is the easier it is to purposefully hit. ⇔ If the cursor is inside an area, the bigger this area is and the farther away its borders are, the harder it is to accidentally leave.