Why does the Fn key lower brightness on my Ubuntu? (Magic Keyboard)

Bersan

10/10/23, 6:55 PM

I'm trying to understand what is going on. I'm running xev to debug this issue.

For a normal key, like ESC, the output of xev is:

KeyPress event, serial 37, synthetic NO, window 0x5800001,
    root 0x7c0, subw 0x0, time 5520877, (82,81), root:(3374,285),
    state 0x10, keycode 9 (keysym 0xff1b, Escape), same_screen YES,
    XLookupString gives 1 bytes: (1b) "
mbLookupString gives 1 bytes: (1b) "
FilterEvent returns: False

But with Fn, the result is:

FocusOut event, serial 37, synthetic NO, window 0x5800001,
    mode NotifyGrab, detail NotifyAncestor

FocusOut event, serial 37, synthetic NO, window 0x5800001,
    mode NotifyUngrab, detail NotifyPointer

FocusIn event, serial 37, synthetic NO, window 0x5800001,
    mode NotifyUngrab, detail NotifyAncestor

KeymapNotify event, serial 37, synthetic NO, window 0x0,
    keys:  4294967232 0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   
           0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0

I wanted to remap the key using the xkb file, as explained here, but it's not evident how to do for the Fn.

1 + 0

keyboard

Score:1

Ubuntu

Bersan

10/11/23, 4:56 PM

Turns out the key was being captured by another application, as described here, namely, gnome-settings-daemon.

I installed sudo apt install dconf-editor, and then I could change the binding of the key:

/org/gnome/settings-daemon/plugins/media-keys/screen-brightness-down-static

and I set it to ''. After restarting the computer, the key did not change my screen brightness anymore, and the output of xev for the key is:

KeyPress event, serial 37, synthetic NO, window 0x2400001,
    root 0x7c0, subw 0x0, time 27282496, (170,174), root:(3443,1424),
    state 0x10, keycode 232 (keysym 0x1008ff03, XF86MonBrightnessDown), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

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EN: Why does the Fn key lower brightness on my Ubuntu? (Magic Keyboard)

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