鼠标移过获取控件句柄、类名、坐标

procedure TForm1.Timer1Timer(Sender: TObject);
var
  H:HWND;
  arr:array[0..254] of char;
  Rt:TRect;
  pt:TPoint;
  ca:TCanvas;
begin
  ca:=TCanvas.Create ;
  ca.Handle :=GetDc(0);
  if GetCursorPos(pt) then begin     //将鼠标位置写入pt
    label1.Caption :='鼠标位置：'+inttostr(pt.x)+','+inttostr(pt.y);
    h:=WindowFromPoint(pt);    //获取鼠标所位置控件的句柄
    GetClassName(h,arr,length(arr));   //取类名
    labelededit1.Text :=inttostr(h);
    labelededit2.Text :=arr;
    GetWindowRect(h,Rt);    //取坐标
    RedrawWindow(0, screen.DesktopRect, 0, RDW_ERASE or RDW_INVALIDATE or RDW_ALLCHILDREN);
//    sendmessage(h,wm_setredraw,0,0);
    Sleep(110);
    ca.Pen.Color :=clBlue;
    ca.Pen.Width :=5;
    ca.polyline([
          rt.TopLeft,
          point(rt.Right,rt.top),
          rt.BottomRight,
          point(rt.Left,rt.Bottom),
          rt.TopLeft
          ]);
    label3.Caption :=inttostr(rt.top)+','+inttostr(rt.Right );
    oldrt:=rt;
  end;
  ca.Free;
end;