You could try to use "xev" to see how many keys are pressed. But make sur you quit KMix before running xev, because otherwise KMix might steal the KeyPress- and KeyRelase-Event of the volume keys.
You could try to use "xev" to see how many keys are pressed. But make sur you quit KMix before running xev, because otherwise KMix might steal the KeyPress- and KeyRelase-Event of the volume keys.