1. Open any other program.
2. Open Arma3 in a window (start without -noPause startup parameter)
3. Open the mission editor
4. Place a player unit, preview the mission
5. Push Esc
6. In expression field enter and execute: foo = 0
6. In one watch field enter: foo
7. In another watch field enter: [] spawn {foo = foo + 1}
8. Memorize approximate value of foo, then Alt-tab to other program
9. Make a cup of coffee
10. Alt-tab back to Arma3, compare memorized value against reported value