+
+// ----------------------------------------------------------------------------
+// multi sample support
+// ----------------------------------------------------------------------------
+
+// this macro defines a variable of type "name_t" called "name" and initializes
+// it with the pointer to WGL function "name" (which may be NULL)
+#define wxDEFINE_WGL_FUNC(name) \
+    name##_t name = (name##_t)wglGetProcAddress(#name)
+
+/* static */
+bool wxGLCanvasBase::IsExtensionSupported(const char *extension)
+{
+    static const char *s_extensionsList = (char *)wxUIntPtr(-1);
+    if ( s_extensionsList == (char *)wxUIntPtr(-1) )
+    {
+        typedef const char * (WINAPI *wglGetExtensionsStringARB_t)(HDC hdc);
+
+        wxDEFINE_WGL_FUNC(wglGetExtensionsStringARB);
+        if ( wglGetExtensionsStringARB )
+        {
+            s_extensionsList = wglGetExtensionsStringARB(wglGetCurrentDC());
+        }
+        else
+        {
+            typedef const char * (WINAPI * wglGetExtensionsStringEXT_t)();
+
+            wxDEFINE_WGL_FUNC(wglGetExtensionsStringEXT);
+            if ( wglGetExtensionsStringEXT )
+            {
+                s_extensionsList = wglGetExtensionsStringEXT();
+            }
+            else
+            {
+                s_extensionsList = NULL;
+            }
+        }
+    }
+
+    return s_extensionsList && IsExtensionInList(s_extensionsList, extension);
+}
+
+// this is a wrapper around wglChoosePixelFormatARB(): returns the pixel format
+// index matching the given attributes on success or 0 on failure
+static int ChoosePixelFormatARB(HDC hdc, const int *attribList)
+{
+    if ( !wxGLCanvas::IsExtensionSupported("WGL_ARB_multisample") )
+        return 0;
+
+    typedef BOOL (WINAPI * wglChoosePixelFormatARB_t)
+                 (HDC hdc,
+                  const int *piAttribIList,
+                  const FLOAT *pfAttribFList,
+                  UINT nMaxFormats,
+                  int *piFormats,
+                  UINT *nNumFormats
+                 );
+
+    wxDEFINE_WGL_FUNC(wglChoosePixelFormatARB);
+    if ( !wglChoosePixelFormatARB )
+        return 0; // should not occur if extension is supported
+
+    int iAttributes[128];
+    int dst = 0; // index in iAttributes array
+
+    #define ADD_ATTR(attr, value) \
+        iAttributes[dst++] = attr; iAttributes[dst++] = value
+
+    ADD_ATTR( WGL_DRAW_TO_WINDOW_ARB,    GL_TRUE );
+    ADD_ATTR( WGL_SUPPORT_OPENGL_ARB,    GL_TRUE );
+    ADD_ATTR( WGL_ACCELERATION_ARB,      WGL_FULL_ACCELERATION_ARB );
+
+    if ( !attribList )
+    {
+        ADD_ATTR( WGL_COLOR_BITS_ARB,          24 );
+        ADD_ATTR( WGL_ALPHA_BITS_ARB,           8 );
+        ADD_ATTR( WGL_DEPTH_BITS_ARB,          16 );
+        ADD_ATTR( WGL_STENCIL_BITS_ARB,         0 );
+        ADD_ATTR( WGL_DOUBLE_BUFFER_ARB,  GL_TRUE );
+        ADD_ATTR( WGL_SAMPLE_BUFFERS_ARB, GL_TRUE );
+        ADD_ATTR( WGL_SAMPLES_ARB,              4 );
+    }
+    else // have custom attributes
+    {
+        #define ADD_ATTR_VALUE(attr) ADD_ATTR(attr, attribList[src++])
+
+        int src = 0;
+        while ( attribList[src] )
+        {
+            switch ( attribList[src++] )
+            {
+                case WX_GL_RGBA:
+                    ADD_ATTR( WGL_COLOR_BITS_ARB, 24 );
+                    ADD_ATTR( WGL_ALPHA_BITS_ARB,  8 );
+                    break;
+
+                case WX_GL_BUFFER_SIZE:
+                    ADD_ATTR_VALUE( WGL_COLOR_BITS_ARB);
+                    break;
+
+                case WX_GL_LEVEL:
+                    if ( attribList[src] > 0 )
+                    {
+                        ADD_ATTR( WGL_NUMBER_OVERLAYS_ARB, 1 );
+                    }
+                    else if ( attribList[src] <0 )
+                    {
+                        ADD_ATTR( WGL_NUMBER_UNDERLAYS_ARB, 1 );
+                    }
+                    //else: ignore it
+
+                    src++; // skip the value in any case
+                    break;
+
+                case WX_GL_DOUBLEBUFFER:
+                    ADD_ATTR( WGL_DOUBLE_BUFFER_ARB, GL_TRUE );
+                    break;
+
+                case WX_GL_STEREO:
+                    ADD_ATTR( WGL_STEREO_ARB, GL_TRUE );
+                    break;
+
+                case WX_GL_AUX_BUFFERS:
+                    ADD_ATTR_VALUE( WGL_AUX_BUFFERS_ARB );
+                    break;
+
+                case WX_GL_MIN_RED:
+                    ADD_ATTR_VALUE( WGL_RED_BITS_ARB );
+                    break;
+
+                case WX_GL_MIN_GREEN:
+                    ADD_ATTR_VALUE( WGL_GREEN_BITS_ARB );
+                    break;
+
+                case WX_GL_MIN_BLUE:
+                    ADD_ATTR_VALUE( WGL_BLUE_BITS_ARB );
+                    break;
+
+                case WX_GL_MIN_ALPHA:
+                    ADD_ATTR_VALUE( WGL_ALPHA_BITS_ARB );
+                   break;
+
+                case WX_GL_DEPTH_SIZE:
+                    ADD_ATTR_VALUE( WGL_DEPTH_BITS_ARB );
+                    break;
+
+                case WX_GL_STENCIL_SIZE:
+                    ADD_ATTR_VALUE( WGL_STENCIL_BITS_ARB );
+                    break;
+
+               case WX_GL_MIN_ACCUM_RED:
+                    ADD_ATTR_VALUE( WGL_ACCUM_RED_BITS_ARB );
+                    break;
+
+                case WX_GL_MIN_ACCUM_GREEN:
+                    ADD_ATTR_VALUE( WGL_ACCUM_GREEN_BITS_ARB );
+                    break;
+
+                case WX_GL_MIN_ACCUM_BLUE:
+                    ADD_ATTR_VALUE( WGL_ACCUM_BLUE_BITS_ARB );
+                    break;
+
+                case WX_GL_MIN_ACCUM_ALPHA:
+                    ADD_ATTR_VALUE( WGL_ACCUM_ALPHA_BITS_ARB );
+                    break;
+
+                case WX_GL_SAMPLE_BUFFERS:
+                    ADD_ATTR_VALUE( WGL_SAMPLE_BUFFERS_ARB );
+                    break;
+
+                case WX_GL_SAMPLES:
+                    ADD_ATTR_VALUE( WGL_SAMPLES_ARB );
+                    break;
+            }
+        }
+
+        #undef ADD_ATTR_VALUE
+    }
+
+    #undef ADD_ATTR
+
+    iAttributes[dst++] = 0;
+
+    int pf;
+    UINT numFormats = 0;
+    if ( !wglChoosePixelFormatARB(hdc, iAttributes, NULL, 1, &pf, &numFormats) )
+    {
+        wxLogLastError(_T("wglChoosePixelFormatARB"));
+        return 0;
+    }
+
+    return pf;
+}
+