The configuration file kcminput, group Mouse is parsed to decide whether
pointer devices should be in left handed mode. The config is applied
whenever a new device is added.
In addition the Connection listens to KGlobalSettings for a mouse
settings changed signal which might be emitted by the mouse KCM.
When such a signal is emitted, all pointer devices are reconfigured.
This allows to change the mouse handed settings on Wayland.