No swap interval on composition.

src/wgl_context.c

@@ -533,6 +533,13 @@ void _glfwPlatformSwapInterval(int interval)
 {
     _GLFWwindow* window = _glfwCurrentWindow;
 
+    if (_glfwIsCompositionEnabled())
+    {
+        // Don't enabled vsync when desktop compositing is enabled, as it leads
+        // to frame jitter
+        return;
+    }
+
     if (window->wgl.EXT_swap_control)
         window->wgl.SwapIntervalEXT(interval);
 }

src/win32_init.c

@@ -86,6 +86,13 @@ static GLboolean initLibraries(void)
             GetProcAddress(_glfw.win32.user32.instance, "SetProcessDPIAware");
     }
 
+    _glfw.win32.dwmapi.instance = LoadLibrary(L"dwmapi.dll");
+    if (_glfw.win32.dwmapi.instance)
+    {
+        _glfw.win32.dwmapi.DwmIsCompositionEnabled = (DWMISCOMPOSITIONENABLED_T)
+            GetProcAddress(_glfw.win32.dwmapi.instance, "DwmIsCompositionEnabled");
+    }
+
     return GL_TRUE;
 }
 
@@ -107,6 +114,21 @@ static void freeLibraries(void)
 //////                       GLFW internal API                      //////
 //////////////////////////////////////////////////////////////////////////
 
+// Returns whether desktop compositing is enabled
+//
+BOOL _glfwIsCompositionEnabled(void)
+{
+    BOOL enabled;
+
+    if (!_glfw_DwmIsCompositionEnabled)
+        return FALSE;
+
+    if (_glfw_DwmIsCompositionEnabled(&enabled) != S_OK)
+        return FALSE;
+
+    return enabled;
+}
+
 // Returns a wide string version of the specified UTF-8 string
 //
 WCHAR* _glfwCreateWideStringFromUTF8(const char* source)

src/win32_platform.h

@@ -72,6 +72,9 @@
 #ifndef WM_MOUSEHWHEEL
  #define WM_MOUSEHWHEEL 0x020E
 #endif
+#ifndef WM_DWMCOMPOSITIONCHANGED
+ #define WM_DWMCOMPOSITIONCHANGED 0x031E
+#endif
 
 
 //========================================================================
@@ -104,6 +107,10 @@ typedef DWORD (WINAPI * TIMEGETTIME_T) (void);
 typedef BOOL (WINAPI * SETPROCESSDPIAWARE_T)(void);
 #define _glfw_SetProcessDPIAware _glfw.win32.user32.SetProcessDPIAware
 
+// dwmapi.dll function pointer typedefs
+typedef HRESULT (WINAPI * DWMISCOMPOSITIONENABLED_T)(BOOL*);
+#define _glfw_DwmIsCompositionEnabled _glfw.win32.dwmapi.DwmIsCompositionEnabled
+
 
 // We use versioned window class names in order not to cause conflicts
 // between applications using different versions of GLFW
@@ -186,10 +193,16 @@ typedef struct _GLFWlibraryWin32
 
     // user32.dll
     struct {
-        HINSTANCE            instance;
+        HINSTANCE       instance;
         SETPROCESSDPIAWARE_T SetProcessDPIAware;
     } user32;
 
+    // dwmapi.dll
+    struct {
+        HINSTANCE       instance;
+        DWMISCOMPOSITIONENABLED_T DwmIsCompositionEnabled;
+    } dwmapi;
+
     struct {
         char*           name;
     } joystick[GLFW_JOYSTICK_LAST + 1];
@@ -212,6 +225,9 @@ typedef struct _GLFWmonitorWin32
 // Prototypes for platform specific internal functions
 //========================================================================
 
+// Desktop compositing
+BOOL _glfwIsCompositionEnabled(void);
+
 // Wide strings
 WCHAR* _glfwCreateWideStringFromUTF8(const char* source);
 char* _glfwCreateUTF8FromWideString(const WCHAR* source);

src/win32_window.c

@@ -606,6 +606,20 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
             }
             break;
         }
+
+        case WM_DWMCOMPOSITIONCHANGED:
+        {
+            if (_glfwIsCompositionEnabled())
+            {
+                _GLFWwindow* previous = _glfwPlatformGetCurrentContext();
+                _glfwPlatformMakeContextCurrent(window);
+                _glfwPlatformSwapInterval(0);
+                _glfwPlatformMakeContextCurrent(previous);
+            }
+
+            // TODO: Restore vsync if compositing was disabled
+            break;
+        }
     }
 
     return DefWindowProc(hWnd, uMsg, wParam, lParam);