Is this what we talk about ?
There are two bloks because i cant figure out wich 'one' is meant in "Now make it check variable 'one' is equal to zero."
Subevents run if there parent(s) is (are) True.
Under the left mouse, the OR-subs only and only run if te local var = zero.
Under the right mouse, the OR-subs can never ever run because you stated that de global var should be 1.