Use the configured Volume Step value for slider page steps
This makes all operations which move the volume in steps - hot keys, mouse wheel over the system tray icon, and slider page steps - use the same step value. Improve the interface between the KMix application and the Volume class, by adding Volume::setVolumeStep() to set the value. There is no need for a getter function since a value can be obtained from Volume::volumeStep(). Eliminates some public static variables that looked like constants. Add an explanatory tool tip to the Volume Step configuration spin box.
Showing with 66 additions and 37 deletions