PHPStorm has this great feature where you can double-tap the shift key to open the “Search Everywhere” utility (or at least that’s how I’ve configured my PHPStorm). It’s wonderful and I use it all day. I wanted the same behavior in some of my other applications but quickly realized it’s not achievable out-of-the-box, even with Keyboard Maestro. I tried to use the double-tap usb device key as a trigger but it didn’t work. I ended up solving the problem using Karabiner Elements.

The idea is simple: Use Karabiner Elements to turn a double-tapped left shift into a hotkey I’d not realistically have set up in any application, then use that hotkey as the hotkey in Keyboard Maestro. I chose <cmd-shift-opt-ctrl-f>.

First, here is the code, which you can create as a Complex Modification in Karabiner Elements: