Using Automator to change System Preference when opening an app

Question

Hello everyone,
I have been using a Mac for a good 8 years now and I'm a happy user. I recently found out about Automator ('hey what is this little robot for?') and what it can do, yet I lack the knowledge of finding out what I must do to make a script to perform the following thing:
When I launch an app (FL Studio), I want the box checked next to 'Use F1 and F2 as standard function keys' in the Keyboard preferences pane in the System Preferences app.
When I close the same app (FL Studio), I want the box unchecked next to 'Use F1 and F2 as standard function keys' in the Keyboard preference pane in the System Preferences app.
I have found several other topics about this subject, however, those were about scripts when logging in to your computer, and not upon opening/closing an app. Please note that I am seeking for the setting to be changed when the app is opened and closed.
I hope you can help,
Sander

Answer 1

This kind of question comes up a lot - how to run a script when an application launches/quits.
The short answer is that it's not easy to do directly, unless the application itself supports launching scripts on startup/quit (hint: few do).
Fortunately, a little difference in thinking can give you the same effect.
Rather than trying to have your script trigger AFTER the app launches, rethink your process to a script that FIRST changes the preference, THEN launches the app. You get the same result but about 14 billion times easier to implement.
In this case, write a script to set the function key preference, then launch FL Studio. The script can then hang around to wait for the app to quit and reset the pref.
Furthermore, don't try to do this the human way (open System preferences, select Keyboard, check the box). You can set the preference directly via the defaults command line utility:
on run
  do shell script "defaults write .GlobalPreferences com.apple.keyboard.fnState 1"
  tell application "FL Studio" to activate
end run
Resetting the preference is a little trickier since you need to detect when FL Studio has quit. You can do this with an idle() handler in your script that hangs around, periodically checking if the app is still running and then taking action:
on idle
  tell application "System Events"
  if (name of every application process) contains "FL Studio" then
  -- app is still running, so come back and check later:
  return 10
  else
  do shell script "defaults write .GlobalPreferences com.apple.keyboard.fnState 0"
  tell me to quit
  end if
  end tell
end idle
Putting these together in a Stay Open script should do much of what you want.