Heya AhabGreybeard, thanks for the response!
I was able to figure out how to after a few hours of reading some info within the topic links you provided and a tutorial on Youtube on how to configure them.
For those who might be using MATE, I did the following to get it working:
My initial problem was that I didn’t know which buttons my Wacom Express Keys were assigned to, so I found that Krita’s Tablet Tester (Config > Tablet > Test Tablet) can detect what the numbers of the buttons are (for example, my stylus’ buttons are assigned Button 2 or Button 4).
What I did find is it’s inaccurate, but it did help point me to the right direction.
Next, the command are the pretty simple.
Use xsetwacom --list devices to find the device name of the connected tablet.
On mine, it results to this:
The next thing you want to do is to tell the terminal to assign certain key combinations on your graphic tablet’s Express Keys.
Which brings a sample code: xsetwacom set "Wacom Intuos PT M Pad pad" Button 3 "key +space"
You just replace the device name with the appropriate ones as per the result of the --list devices command.
Now, I only have 4 buttons in my tablet, but the button numbers are not 1, 2, 3 and 4. I don’t know how else to get a list of which numbers the buttons are assigned to, so I had to make a trial and error. In the end, my button numbers are actually 1, 3, 8 and 9. Don’t worry, if you input the incorrect number, it wouldn’t push through anyway. So I just kept guessing.
When assigning key combinations, + and - signs do matter as well.
For example, I assigned the hand tool (space bar) to Button 3. I originally encoded it as xsetwacom set "Wacom Intuos PT M Pad pad" Button 3 "key space" and it didn’t work because the click was being read as a “single click” instead of “hold”.
In order to tell xsetwacom that I meant for it to be “hold”, I have to put a plus sign (+) before the space.
So it becomes xsetwacom set "Wacom Intuos PT M Pad pad" Button 3 "key +space"
The complete description is here on the manual, under the Buttons section: https://linux.die.net/man/1/xsetwacom
Other links that may be useful:
GitHub - linuxwacom/libwacom: libwacom is a tablet description library (for your tablet configuration)
https://www.youtube.com/watch?v=HEZK7reJqoQ&t=458s (the Youtube tutorial I referenced from)
I hope this helps someone in the future!
