win32: Add a config file only DWM tweaks option.

win32/wconfig.cpp

@@ -759,6 +759,7 @@ void WinRegisterConfigItems()
 	AddBoolC("HideMenu", GUI.HideMenu, false, "true to auto-hide the menu bar on startup.");
 	AddBoolC("Vsync", GUI.Vsync, false, "true to enable Vsync");
 	AddBoolC("ReduceInputLag", GUI.ReduceInputLag, false, "true to reduce input lag by hard synchronization");
+    AddBoolC("DWMTweaks", GUI.DWMTweaks, false, "true to try and avoid DWM stutter");
 	AddBoolC("FilterMessageFont", GUI.filterMessagFont, true, "true to filter message font with EPX on 2x/3x scales if MessagesInImage is false)");
 #undef CATEGORY
 #define CATEGORY "Settings"

win32/win32_display.cpp

@@ -118,6 +118,19 @@ bool WinDisplayReset(void)
 		S9xGraphicsDeinit();
 		S9xSetWinPixelFormat ();
 		S9xGraphicsInit();
+
+        if (GUI.DWMTweaks)
+        {
+            HMODULE dwmlib = LoadLibrary(TEXT("dwmapi"));
+            if (dwmlib)
+            {
+                HRESULT(WINAPI *dwmEnableMMCSS)(BOOL) = (HRESULT(WINAPI *)(BOOL))GetProcAddress(dwmlib, "DwmEnableMMCSS");
+                dwmEnableMMCSS(true);
+                return true;
+            }
+            MessageBox(GUI.hWnd, TEXT("Couldn't enable MMCSS for DWM"), TEXT("Warning"), MB_OK | MB_ICONWARNING);
+        }
+
 		return true;
 	} else {
 		MessageBox (GUI.hWnd, Languages[ GUI.Language].errInitDD, TEXT("Snes9X - Display Failure"), MB_OK | MB_ICONSTOP);

win32/wsnes9x.h

@@ -156,6 +156,7 @@ struct sGUI {
 	bool Vsync;
 	bool ReduceInputLag;
 	bool shaderEnabled;
+    bool DWMTweaks;
 	TCHAR D3DshaderFileName[MAX_PATH];
 	TCHAR OGLshaderFileName[MAX_PATH];