--- a/src/video/cocoa/cocoa_v.h
+++ b/src/video/cocoa/cocoa_v.h
@@ -42,9 +42,41 @@
 };
 
 
-
+/**
+ * Generic display driver for cocoa
+ * On grounds to not duplicate some code, it contains a few variables
+ * which are not used by all device drivers.
+ */
 class CocoaSubdriver {
 public:
+	int device_width;
+	int device_height;
+	int device_depth;
+
+	int window_width;
+	int window_height;
+	int window_pitch;
+
+	int buffer_depth;
+	void *pixel_buffer;   // used for direct pixel access
+	void *window_buffer;  // has colour translation from palette to screen
+	id window;            // pointer to window object
+
+#	define MAX_DIRTY_RECTS 100
+	Rect dirty_rects[MAX_DIRTY_RECTS];
+	int num_dirty_rects;
+	uint32 palette[256];
+
+	bool active;
+	bool setup;
+
+	id cocoaview;         // pointer to view object
+
+	/* Separate driver vars for Quarz
+	 * Needed here in order to avoid much code duplication */
+	CGContextRef cgcontext;
+
+	/* Driver methods */
 	virtual ~CocoaSubdriver() {}
 
 	virtual void Draw(bool force_update = false) = 0;

--- a/src/video/cocoa/fullscreen.mm
+++ b/src/video/cocoa/fullscreen.mm
@@ -149,22 +149,11 @@
 }
 
 class FullscreenSubdriver: public CocoaSubdriver {
-	int                device_width;
-	int                device_height;
-	int                device_depth;
-	int                window_pitch;
-	void              *window_buffer;
-	void              *pixel_buffer;
-
 	CGDirectDisplayID  display_id;         ///< 0 == main display (only support single display)
 	CFDictionaryRef    cur_mode;           ///< current mode of the display
 	CFDictionaryRef    save_mode;          ///< original mode of the display
 	CGDirectPaletteRef palette;            ///< palette of an 8-bit display
 
-	#define MAX_DIRTY_RECTS 100
-	Rect dirty_rects[MAX_DIRTY_RECTS];
-	int num_dirty_rects;
-
 
 	/* Gamma functions to try to hide the flash from a res switch
 	 * Fade the display from normal to black

--- a/src/video/cocoa/wnd_quartz.mm
+++ b/src/video/cocoa/wnd_quartz.mm
@@ -84,37 +84,7 @@
 @end
 
 class WindowQuartzSubdriver: public CocoaSubdriver {
-	int device_width;
-	int device_height;
-
-	int window_width;
-	int window_height;
-
-	int buffer_depth;
-
-	void *pixel_buffer;
-	void *window_buffer;
-
-	id window;
-
-	#define MAX_DIRTY_RECTS 100
-	Rect dirty_rects[MAX_DIRTY_RECTS];
-	int num_dirty_rects;
-
-	uint32 palette[256];
-
-public:
-	bool active;
-	bool setup;
-
-	id cocoaview;
-	CGContextRef cgcontext;
-
 private:
-	void GetDeviceInfo();
-
-	bool SetVideoMode(int width, int height);
-
 	/**
 	 * This function copies 8bpp pixels from the screen buffer in 32bpp windowed mode.
 	 *
@@ -125,6 +95,9 @@
 	 */
 	void BlitIndexedToView32(int left, int top, int right, int bottom);
 
+	virtual void GetDeviceInfo();
+	virtual bool SetVideoMode(int width, int height);
+
 public:
 	WindowQuartzSubdriver(int bpp);
 	virtual ~WindowQuartzSubdriver();

--- a/src/video/cocoa/wnd_quickdraw.mm
+++ b/src/video/cocoa/wnd_quickdraw.mm
@@ -73,38 +73,7 @@
 @end
 
 class WindowQuickdrawSubdriver: public CocoaSubdriver {
-	int device_width;
-	int device_height;
-	int device_depth;
-
-	int window_width;
-	int window_height;
-	int window_pitch;
-
-	int buffer_depth;
-
-	void *pixel_buffer;
-	void *window_buffer;
-
-	id window;
-
-	#define MAX_DIRTY_RECTS 100
-	Rect dirty_rects[MAX_DIRTY_RECTS];
-	int num_dirty_rects;
-
-	uint32 palette[256];
-
-public:
-	bool active;
-	bool setup;
-
-	id cocoaview;
-
 private:
-	void GetDeviceInfo();
-
-	bool SetVideoMode(int width, int height);
-
 	/**
 	 * This function copies 32bpp pixels from the screen buffer in 16bpp windowed mode.
 	 *
@@ -138,6 +107,8 @@
 	inline void BlitToView(int left, int top, int right, int bottom);
 	void DrawResizeIcon();
 
+	virtual void GetDeviceInfo();
+	virtual bool SetVideoMode(int width, int height);
 
 public:
 	WindowQuickdrawSubdriver(int bpp);