I'd installed a clean copy of developers-stable 64-bit on June 4 and found that Enable/Disable Touchpad was greyed out. I'd been hoping that a more recent update would clean up this problem but so far that has not happened. This is on a Dell XPS 13.

Yesterday I scrubbed developers-stable and installed the latest useredition hoping that Touchpad settings were working there. They used to. I was dismayed to find that settings were still greyed out. It is so frustrating when you accidentally brush the touchpad when you've got a mouse plugged in and you end up somewhere else on the screen.

Love Neon. When it's working properly it's my dream OS. I'm presently downloading the LTS version. Fingers crossed . . .

EDIT: Fixed in user 5.13.2

Are you using X or Wayland?

Probably X? Whatever the default is. Just booted up the LTS live and touchpad settings are active. Installing now.

I installed KDE neon LTS 5.8

Plasma version: 5.8.7
Frameworks: 5.34.0
Qt version: 5.7.1
Kernel verison: 4.8.0-53-generic
OS type: 64 bit

Touchpad settings were active and I was able to select "Disable touchpad when mouse is plugged in".
At this point from the konsole I did an "apt update" and then an "apt dist-upgrade", followed by an "apt autoremove". I had to repeat the update and dist-upgrade a couple of times before it went to completion.

I now have KDE neon LTS 5.12

Plasma version: 5.12.5
Framework: 5.47.0
Qt version: 5.11.0
Kernel version: 4.13.0-45-generic
OS type: 64 bit.

Re-booting brings me to the old desktop image which is not as beautiful as the new one but the Touchpad is still deactivated when I've got the mouse plugged in. Definitely a trade off I can live with.

How do I determine if I'm using X or Wayland?