TNCCanvas = class(TCanvas)
  private
    FDeviceContext: HDC;
    FWindowHandle : HWnd;
    function     GetWindowRect: TRect;
  protected
    procedure    CreateHandle; override;
    procedure    FreeHandle;
  public
    constructor  Create(aWindow: hWnd);
    destructor   Destroy; override;
    property     WindowRect: TRect read GetWindowRect;
  end;

{ TNCCanvas - Object }
constructor TNCCanvas.Create(aWindow: hWnd);
begin
  inherited Create;
  FWindowHandle:=aWindow;
end;

destructor  TNCCanvas.Destroy;
begin
  FreeHandle;
  inherited Destroy;
end;

procedure TNCCanvas.CreateHandle;
begin
  if FWindowHandle=0 then inherited CreateHandle else
  begin
    if FDeviceContext = 0 then
       FDeviceContext := GetWindowDC(FWindowHandle);
    Handle := FDeviceContext;
  end;
end;

procedure TNCCanvas.FreeHandle;
begin
  Handle := 0;
  if FDeviceContext <> 0 then
  begin
    ReleaseDC(FWindowHandle, FDeviceContext);
    FDeviceContext:=0;
  end;
end;

function TNCCanvas.GetWindowRect:TRect;
begin
  winProcs.GetWindowRect(FWindowHandle,Result);
  With Result do
  begin
    Right:=Pred(Right-Left);
    Bottom:=Pred(Bottom-Top);
    Left:=0; Top:=0;
  end;
end;