Pulseaudio plugin 0.4.1 mute button reacts to button-up event

Submitted by haarp

Assigned to Andrzej

Link to original bug (#14590)

Description

When I open the plugin's dialog, click and hold the volume bar, move it all the way to the right, then release the button while hovering on top of the mute button, the mute button reacts.

It should only react when the button-down event has been executed while hovering on top of the button beforehand.