Best Way to Toggle "Use F1, F2, Etc Keys as Standard Function Keys"

[Joseki]

Or simply :

How to Use Function Keys (aka Hardware Keys) as Triggers

I saw some people asking questions about this so I hope this will be useful. Function keys are mostly used to change some hardware settings: adjusting luminosity/sound etc…This is the « normal » behavior. Goal : Use the function keys to launch macros but only in RandomApplication. Keep their normal behavior everywhere else. Problem: Keyboard Maestro has no possibility to capture the hardware keypresses. Solution: disable hardware keys in system setting and recreate their function in Keyboar…