WinAPI: GetParent - 获取指定窗口的父窗口句柄 
//声明:
GetParent(
  hWnd: HWND {窗口句柄}
): HWND;     {返回父窗口句柄}


//举例:
procedure TForm1.Button1Click(Sender: TObject);
var
  h1,h2: HWND;
begin
  h1 := GetParent(Button1.Handle);
  h2 := Panel1.Handle;
  ShowMessage(IntToStr(h1)); {590862}
  ShowMessage(IntToStr(h2)); {590862}

  h1 := GetParent(Panel1.Handle);
  h2 := Self.Handle;
  ShowMessage(IntToStr(h1)); {459824}
  ShowMessage(IntToStr(h2)); {459824}

  ShowMessage(IntToStr(GetParent(Handle))); {0}
end;


//效果图: