Disabling special keys

[Jim]

I've got Kubuntu 20.04 and  there's no /usr/src/linux.    In /usr/src 
there are several directories with linux in the name, one is 
linux-headers-5.4.0-48.  In each one there's a drivers/hid directory, 
but I didn't find the maker of the keyboard.  I bought it off that 
website named after the big river in Brazil.  The brand  name was 
Nulea.  However, I did find a way to stop that key from annoying me when 
I hit it by accident.  I took the key off and removed that little bit of 
plastic that was under the key and replaced it.

About a year ago, I  wanted to be able to access the degree (°) without 
launching an app to show  the seldom used characters then finding the 
one I wanted and copying it and pasting it.  I found a way to modify the 
windows key so if I hold it down while pressing o twice, I get °.   The 
problem is that I forgot how or where I found out how to do that.  Any 
idea how to do that?  Thanks.

On 7/12/22 17:03, Matt Graham via PLUG-discuss wrote:
> On 2022-07-12 14:30, Jim via PLUG-discuss wrote:
>> one is a printer key.  When I press it xev tells me it's sending
>> the Control_L and p codes at the same time. I want to remap it
> . so it sends only one keycode.  Here's what xev shows when I
>> press it.
>> KeyPress event,
>>     state 0x10, keycode 37 (keysym 0xffe3, Control_L)
>> KeyPress event,
>>     state 0x14, keycode 33 (keysym 0x70, p)
>> KeyRelease event,
>>     state 0x14, keycode 37 (keysym 0xffe3, Control_L)
>> KeyRelease event,
>>     state 0x10, keycode 33 (keysym 0x70, p)
>> If I disable keycode 33, the p key also doesn't work.  Is there
>> some way to get it to send just one code?
>
> If this is anything like other HID devices that I've seen that do 
> this, it will not be easy.  I have a mouse where one of the extra 
> buttons generates KeyPress events for Shift_L, then Meta_L, then 
> KeyRelease events for ISO_Left_Tab, Meta_L, and Shift_L.  I assume 
> that this is being done at a rather low level in the device.  HID 
> things can send key events if they want, that's part of being HID.  
> There is usually no way (or no obvious way?) to change their 
> multiple-key event sending.
>
> I have not had a great deal of trouble with this because it's easy to 
> not hit that button.  If I were really motivated to fix it, I'd go 
> digging in /usr/src/linux/drivers/hid/ and find the file that contains 
> the code for your manufacturer's devices.  Then learn the HID stuff 
> and set things up so that if the scancode for this key comes in, you 
> send 1 event of Xfree86_Print (or whatever other keysym you think is 
> appropriate) instead of Control_L and p. Hacky, but you have the 
> option.  The hid-prodikeys.c file shows an example of handling a USB 
> keyboard that also has piano keys and modifier keys, it's long, but it 
> may be a useful file to look at.
>