True to its name, Caffeine is like coffee for your computer. Every 59 seconds, it simulates the press of the F15 key to keep your machine out of screensaver/standby mode. F15? It’s a key recognized by Windows, but virtually nonexistent on actual keyboards, and therefore not likely to be assigned in any programs you use. In other words, repeated F15 presses shouldn’t mess with anything you’re doing. If it does, however, there’s a command-line option that will use the Shift key instead.