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March 29th, 2019 08:00
Caps + Shift + 2 doesn't work
I have a Dell Precision 5530 (approximately the same as an XPS 9570). I'm running Linux and I've set up some modifier keys:
Control + number - switches to the numbered workspace
Control + Shift + number - sends the current window to the numbered workspace
I've also mapped CapsLock as Control.
Everything works except one key combination: Control + Shift + 2 does nothing. I've used the linux command `showkeys` in a TTY to determine that:
When pressing the keys individually, I see keycodes in the terminal.
If I press any two keys of Caps, Shift, 2 I see the appropriate keycodes in the terminal.
If I press Caps + Shift + 2 in any order, the last key pressed is not recorded.
If I press Caps + Shift + a number that isn't 2, in any order, all three keys are recorded.
Is this a hardware limitation or is there a problem with the keyboard?
jphughan
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March 29th, 2019 09:00
Probably a hardware limitation. The way key presses are detected (and anti-ghosting is implemented) on certain keyboard designs can cause some key combinations not to register even though other very similar combinations (like using other numbers) work just fine.
peschkaj78
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March 29th, 2019 21:00
jphughan
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March 29th, 2019 22:00
I don’t have a way to answer that, and short of just testing it, I’m not sure there’s a way to know in advance. Whether a given key combination will work depends on the exact details of how the keyboard is designed, and that type of spec just isn’t published anywhere that I’ve seen. The only exception would be NKRO keyboards that are explicitly designed to correctly register any key combination of any number of keys being pressed simultaneously, but most keyboards don’t support that. Instead, they support “up to” a certain number of keys being pressed simultaneously, but that doesn’t mean they support all possible combinations of that number of keys. And again, which specific combinations they support isn’t something you’ll find published in specs.