The script runs again when you release and press the scroll
button again. This time the "if" argument can't be evaluated to
a null, since we have a definite value (5000) stored in the
up_last_click variable. Lets assume you pressed the button
exactly one quarter (1/4) second after the first press, and lets
step through this script again: up_first_click = getTimer( );
Now the up_first_click variable is updated to a new value by the
"getTImer" action. Since one quarter second translates to 250
ms, up_first_click's new value will be 5250 (5000 + 250 = 5250).
With that done, we move to the "if" condition, and fill in our
numeric values for the up_first_click and up_last_click
variables. 5250 - 5000 = 250 ms. Using this inequality
expression, Mick has set the double-click threshold to 350 ms.
As long as the pause between button presses is equal to or less
than 350 ms, as it is in our example, the "if" argument returns
"true" and its embedded action is executed. If the pause between
cicks is longer than 350 ms, the