WinAPI: GetClassName - 获取指定窗口的类名  
//声明:  
GetClassName(  
  hWnd: HWND;         {指定窗口句柄}  
  lpClassName: PChar; {缓冲区}  
  nMaxCount: Integer  {缓冲区大小}  
): Integer;           {返回类名大小; 失败返回 0}  
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//测试1: 新建一个工程, 主窗口的类名默认是 TForm1, 用程序获取一下看看  
var  
  ps: array[0..254] of Char;  
begin  
  GetClassName(Handle, ps, 255);  
  ShowMessage(ps); {TForm1}  
end;  
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//测试2: 看看 "计算器" 窗口的类名(先启动计算器)  
var  
  h: HWND;  
  ps: array[0..254] of Char;  
begin  
  h := FindWindow(nil, ‘计算器‘); {这句是获取计算器窗口的句柄}  
  GetClassName(h, ps, 255);  
  ShowMessage(ps); {SciCalc}  
end;  
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//测试3: 看看记事本窗口的类名(先重新启动记事本):  
var  
  h: HWND;  
  ps: array[0..254] of Char;  
begin  
  h := FindWindow(nil, ‘无标题 - 记事本‘); {这句是获取记事本窗口的句柄}  
  GetClassName(h, ps, 255);  
  ShowMessage(ps); {Notepad}  
end;