I run Ubuntu 16.04 as a Windows 10 dual boot on a HP with its built-in keyboard.
Specifications in picture
I noticed an annoying keyboard behaviour under Ubuntu. When I press a key, it can happen that the system repeats the key infinitely, even after I released the key. I think this bug only appears, if I press a key for a longer time, but the bug can't be always reproduced by pressing a key over an extended period of time.
This can happen with any key, but mostly I notice it with arrow keys (Annoyingly, sometimes one doesn't see anything, except that the program seems to be unresponsive, because the arrow key command overrules any further input). I can terminate the key repeat by pressing Esc or another arrow key.
I don't know, how to evoke this behaviour on purpose. It is not a computer problem per se - I have never noticed that behaviour, when using the Windows partition. It is also not a problem with the latest update - the problem exists for quite a while, I just happen to ask now.
I also tried this keyboard test from the related question section. Keys were shown as expected and the sticky key problem didn't appear. Which doesn't say much, since it sometimes does not happen for days.
gsettings get org.gnome.desktop.a11y.keyboard stickykeys-enable- this should return 'false'. Also look at this answer, and if you have a USB keyboard around, verify the problem is with the OS rather than the current keyboard
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IBusas suggested by the other thread, you pointed out.