On the screen display volume mixer for LXDE: volume-osd

<!-- Keybinding for Volume management -->
  <keybind key="XF86AudioRaiseVolume">
     <action name="Execute">
      <command>volume-osd up</command>
    </action>
  </keybind>

  <keybind key="XF86AudioLowerVolume">
      <action name="Execute">
       <command>volume-osd down</command>
    </action>
  </keybind>

  <keybind key="XF86AudioMute">
      <action name="Execute">
       <command>volume-osd mute</command>
    </action>
  </keybind>