anchor.diff:  
   implementation
   
  -
   function SetDCPixelFormat(h_DC:HDC; PixelFormat:Integer):boolean;
   var
     nPixelFormat: Integer;
     PixelDepth:integer;
  +  {$IFDEF MSWINDOWS}
     pfd: TPixelFormatDescriptor;
  +  {$ENDIF}
   begin
     PixelDepth := 32; //32bpp is common
  -
  +  {$IFDEF MSWINDOWS}
     with pfd do begin
       nSize           := SizeOf(TPIXELFORMATDESCRIPTOR); // Size Of This Pixel Format Descriptor
       nVersion        := 1;                    // The version of this data structure
  
positive.code: 
    if not SetDCPixelFormat(h_DC, PixelFormat) then
      exit;
  
    h_RC := wglCreateContext(h_DC);
  
    if h_RC = 0 then
    begin
      MessageBox(HWND(nil), 'Unable to create an OpenGL rendering context', 'Error', MB_OK or MB_ICONERROR);
      exit;
    end;
  
    if not wglMakeCurrent(h_DC, h_RC) then
    begin
      MessageBox(HWND(nil), 'Unable to activate OpenGL rendering context', 'Error', MB_OK or MB_ICONERROR);
      exit;
  
negative.code:   ReadImplementationProperties;
  
    PixelFormat := GetMultisamplePixelFormat(h_DC, AntiAliasing);
    {$IFDEF MSWINDOWS}
    wglMakeCurrent(h_DC, 0);
    wglDeleteContext(h_RC);
    {$ENDIF}
    SetContexts(RenderFrame, PixelFormat, h_DC, h_RC);
    ReadExtensions;
    ReadImplementationProperties;
  