anchor.diff:  {$IFDEF VER220} {$DEFINE WDC} {$ENDIF}  // Delphi XE
   interface
   uses
  -  {$IFDEF WDC} OpenGL, {$ENDIF}  dglOpenGL,
  +  dglOpenGL,
     {$IFDEF FPC} GL, LCLIntf, {$ENDIF}
     {$IFDEF MSWindows} Windows, {$ENDIF}
     {$IFDEF Unix} LCLType, glx, {$ENDIF}
  -  sysutils, Forms, KromUtils;
  -
  -type KCode = (kNil=0,kPoint=1,kSpline=2,kSplineAnchor=3,kSplineAnchorLength=4,
  -kPoly=5,kSurface=6,kObject=7,kButton=8);  //1..31 are ok
  +  SysUtils, Forms, KromUtils;
  +
   {$IFDEF Unix}
   type HGLRC = integer;
   type PFD_DRAW_TO_WINDOW = integer;
  
positive.code:     bReserved       := 0;                    // Number of overlay and underlay planes
      dwLayerMask     := 0;                    // Ignored
      dwVisibleMask   := 0;                    // Transparent color of underlay plane
      dwDamageMask    := 0;                     // Ignored
    end;
    {$IFDEF MSWindows}
    nPixelFormat:=ChoosePixelFormat(h_DC, @pfd);
    {$ENDIF}
    {$IFDEF Unix}
    //nPixelFormat:=glXChooseVisual(h_DC, @pfd);
    {$ENDIF}
  
    if nPixelFormat=0 then begin
    MessageBox(0, 'Unable to find a suitable pixel format', 'Error', MB_OK or MB_ICONERROR);
      Result:=false;
      exit;
    end;
    if not SetPixelFormat(h_DC, nPixelFormat, @pfd) then begin
    MessageBox(0, 'Unable to set the pixel format', 'Error', MB_OK or MB_ICONERROR);
      Result:=false;
      exit;
    end;
  {$ENDIF}
  {$IFDEF Unix}
  //TODO some example maybe here
  //http://zengl.googlecode.com/svn-history/r723/trunk/src/zgl_opengl.pas
  //now just create stub:
  begin
    MessageBox(0, 'SetDCPixelFormat failed', 'Error', MB_OK or MB_ICONERROR);
      Result:=false;
      exit;
  {$ENDIF}
  Result:=true;
  end;
  
  
  
negative.code:   glvertex2f(Bx,By);
    glvertex2f(Ax,By);
  end;
  
  
  {Lines are drawn between pixels, thus when AA turned on they get blurred.
  We can negate this by using 0.5 offset
  