Added glfwCopyGLState.

src/cocoa/cocoa_opengl.m

@@ -86,3 +86,12 @@ void* _glfwPlatformGetProcAddress(const char* procname)
     return symbol;
 }
 
+//========================================================================
+// Copies the specified OpenGL state categories from src to dst
+//========================================================================
+
+void _glfwPlatformCopyGLState(_GLFWwindow* src, _GLFWwindow* dst, unsigned long mask)
+{
+    [dst->NSGL.context copyAttributesFromContext:src->NSGL.context withMask:mask];
+}
+

src/internal.h

@@ -310,6 +310,7 @@ void _glfwPlatformSwapInterval(int interval);
 void _glfwPlatformRefreshWindowParams(void);
 int  _glfwPlatformExtensionSupported(const char* extension);
 void* _glfwPlatformGetProcAddress(const char* procname);
+void _glfwPlatformCopyGLState(_GLFWwindow* src, _GLFWwindow* dst, unsigned long mask);
 
 
 //========================================================================

src/opengl.c

@@ -587,3 +587,25 @@ GLFWAPI void glfwGetGLVersion(int* major, int* minor, int* rev)
         *rev = window->glRevision;
 }
 
+
+//========================================================================
+// Copies the specified OpenGL state categories from src to dst
+//========================================================================
+
+GLFWAPI void glfwCopyGLState(GLFWwindow hsrc, GLFWwindow hdst, unsigned long mask)
+{
+    _GLFWwindow* src;
+    _GLFWwindow* dst;
+
+    if (!_glfwInitialized)
+    {
+        _glfwSetError(GLFW_NOT_INITIALIZED, NULL);
+        return;
+    }
+
+    src = (_GLFWwindow*) hsrc;
+    dst = (_GLFWwindow*) hdst;
+
+    _glfwPlatformCopyGLState(src, dst, mask);
+}
+

src/win32/win32_opengl.c

@@ -103,3 +103,14 @@ void* _glfwPlatformGetProcAddress(const char* procname)
     return (void*) wglGetProcAddress(procname);
 }
 
+
+//========================================================================
+// Copies the specified OpenGL state categories from src to dst
+//========================================================================
+
+void _glfwPlatformCopyGLState(_GLFWwindow* src, _GLFWwindow* dst, unsigned long mask)
+{
+    if (!wglCopyContext(src->WGL.context, dst->WGL.context, mask))
+        _glfwSetError(GLFW_PLATFORM_ERROR, "Win32/WGL: Failed to copy OpenGL context attributes");
+}
+

src/x11/x11_opengl.c

@@ -116,3 +116,16 @@ void* _glfwPlatformGetProcAddress(const char* procname)
     return (void*) _glfw_glXGetProcAddress((const GLubyte*) procname);
 }
 
+
+//========================================================================
+// Copies the specified OpenGL state categories from src to dst
+//========================================================================
+
+void _glfwPlatformCopyGLState(_GLFWwindow* src, _GLFWwindow* dst, unsigned long mask)
+{
+    glXCopyContext(_glfwLibrary.X11.display,
+                   src->GLX.context,
+                   dst->GLX.context,
+                   mask);
+}
+