Move DWM enabled test to file where it is used

src/wgl_context.c

@@ -265,6 +265,21 @@ static GLFWbool choosePixelFormat(_GLFWwindow* window,
     return GLFW_TRUE;
 }
 
+// Returns whether desktop compositing is enabled
+//
+static GLFWbool isCompositionEnabled(void)
+{
+    BOOL enabled;
+
+    if (!_glfw_DwmIsCompositionEnabled)
+        return FALSE;
+
+    if (_glfw_DwmIsCompositionEnabled(&enabled) != S_OK)
+        return FALSE;
+
+    return enabled;
+}
+
 
 //////////////////////////////////////////////////////////////////////////
 //////                       GLFW internal API                      //////
@@ -595,7 +610,7 @@ void _glfwPlatformMakeContextCurrent(_GLFWwindow* window)
 void _glfwPlatformSwapBuffers(_GLFWwindow* window)
 {
     // HACK: Use DwmFlush when desktop composition is enabled
-    if (_glfwIsCompositionEnabled() && !window->monitor)
+    if (isCompositionEnabled() && !window->monitor)
     {
         int count = abs(window->context.wgl.interval);
         while (count--)

src/win32_init.c

@@ -290,21 +290,6 @@ static HWND createHelperWindow(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

@@ -262,8 +262,6 @@ typedef struct _GLFWtimeWin32
 GLFWbool _glfwRegisterWindowClass(void);
 void _glfwUnregisterWindowClass(void);
 
-BOOL _glfwIsCompositionEnabled(void);
-
 WCHAR* _glfwCreateWideStringFromUTF8(const char* source);
 char* _glfwCreateUTF8FromWideString(const WCHAR* source);