In Firefox enabling privacy.resistFingerprinting in about:config breaks the detection of Ctrl because with the keydown event the modifier keys (ctrl, alt, shift) is silenced. Testable with the following code from console: ```js document.addEventListener('keydown', function (e) { console.log(e.keyCode) }); ``` So with this the event for Ctrl (keyCode 17) and the other modifier keys are not firing. But I found that with the click event it's still detecting the modifier keys: ```js document.addEventListener('click', function (e) { console.log(e.ctrlKey); }); ``` Hence my suggestion would be to consider switching the Ctrl using hotkeys to the click event if possible, as I suspect others also could run into this limitation.