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Num lock state changes when UVC webcam is plugged in.

Submitted by Alistair Buxton @ali1234

Assigned to Jérôme Guelfucci

Link to original bug (#12694)

Description

To reproduce:

  1. In keyboard settings turn on "restore num lock state at start up"
  2. Open settings editor and create a boolean key "/Default/Numlock" under channel "keyboards". Set it to false.
  3. Plug in a UVC webcam.

Result: Keyboard num lock is turned off.

  1. Change the key to true.
  2. Unplug and plug in the webcam.

Result: Keyboard num lock is turned on.

Impact: My monitor has a built in USB hub. My webcam is plugged in to the USB hub, and appears as an input device. When the monitor goes in to power saving mode the USB hub is turned off. When the monitor turns back on the webcam appears to have just been plugged in.

The result is that whenever my monitor wakes from power saving mode, num lock is changed to whichever state it was in at the last system power off.

Recommendation: Ignore web cams, or save the num lock state at device disconnect, or both.