Preventing Firefox From Entering Safe Mode

Recently I started using yabai + skhd for window management in OS X.

I have set up Caps Lock as a Hyper key using Karabiner elements and dedicated it for yabai + skhd.

Hyper key simply produces the effect of Shift + Alt + Command + Control. Basically, if I press Caps Lock + <something> it will be converted to Shift + Alt + Command + Control + <something>.

I wanted to set up some hotkeys to open applications that I frquently use like Terminal and Browser. I am a Firefox user so I wanted to open Firefox whenever I press Hyper + B. I added an skhd configuration like this:

hyper - b : open "/Applications/Firefox Developer"

But it didn't work as expected. All I got was this:

Firefox Safe Mode prompt screenshot

Firefox was trying to start in Safe Mode. After some research, I came to know that pressing Alt while opening Firefox signals it to open in Safe Mode.

You can reproduce this by executing open "/Applications/Firefox Developer" and pressing Alt immediately before Firefox launches.

Hyper key is the problem here. As I mentioned before Hyper = Shift + Alt + Command + Control and it contains Alt as one of the keys so Firefox was signalled to open in Safe Mode.

Luckily, there is an environment variable MOZ_DISABLE_SAFE_MODE_KEY using which we can prevent Firefox from entering Safe Mode even if Alt key is pressed.

Execute MOZ_DISABLE_SAFE_MODE_KEY=1 open "/Applications/Firefox Developer" and press Alt immediately, you would see that Firefox opening normally.

I fixed my skhd configuration using the same:

hyper - b : export MOZ_DISABLE_SAFE_MODE_KEY=1; open "/Applications/Firefox Developer"


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