#pragma once

#include "OSD\OSD.h"
#include "SliderWnd.h"

class VolumeSlider : public OSD {
public:
    VolumeSlider(HINSTANCE hInstance, Settings &settings);

    void Hide();

private:
    SliderWnd _sWnd;

};

#pragma once

#include "OSD\OSD.h"
#include "MeterWnd\MeterWnd.h"

class VolumeSlider : public OSD {
public:
    VolumeSlider(HINSTANCE hInstance, Settings &settings);

    void Hide();

private:
    MeterWnd _mWnd;

};

--- 
+++ 
@@ -1,7 +1,7 @@
 #pragma once
 
 #include "OSD\OSD.h"
-#include "MeterWnd\MeterWnd.h"
+#include "SliderWnd.h"
 
 class VolumeSlider : public OSD {
 public:
@@ -10,6 +10,6 @@
     void Hide();
 
 private:
-    MeterWnd _mWnd;
+    SliderWnd _sWnd;
 
 };
Use a sliderwnd instance to implement the volume slider
