SendKeys cannot run inside this application

 const  int  WM_GETTEXT = 0x000D;

 const  int  WM_GETTEXTLENGTH = 0x000E;

 [DllImport("user32.dll" , CharSet = CharSet.Auto)]

 static  extern  IntPtr SendMessage(IntPtr hWnd, int  Msg, int  wParam, StringBuilder lParam);

 int  length = SendMessage(TextBoxhWnd, WM_GETTEXTLENGTH, 0, IntPtr.Zero).ToInt32();

 StringBuilder sbtext = new  StringBuilder(length);

 int  hr = SendMessage(TextBoxhWnd, WM_GETTEXT, length, sbtext).ToInt32();

 using  System;

 using  System.Runtime.InteropServices;

 using  System.Threading;

 namespace  _162053

 {

 class  Program 

 {

 const  string  ProgramLocation = @"\\Windows\\system32\\notepad.exe" ;

 const  string  DialogClass = "#32770" ;// (Dialog) 

 const  int  TextBoxId = 15;

 const  int  CancelButtonId = 2;

 const  int  WM_SETTEXT = 0x000C;

 const  int  WM_COMMAND = 0x0111;

 const  int  BN_CLICKED = 0;

 const  int  FileMenuId = 3;

 [DllImport ("user32.dll" , CharSet = CharSet .Auto, SetLastError = true )]

 static  extern  int  GetWindowThreadProcessId(IntPtr  handle, out  int  processId);

 [DllImport ("user32.dll" )]

 static  extern  IntPtr  GetDlgItem(IntPtr  hWnd, int  nIDDlgItem);

 [DllImport ("user32.dll" )]

 static  extern  IntPtr  PostMessage(IntPtr  hWnd, int  Msg, int  wParam, IntPtr  lParam);

 [DllImport ("user32.dll" )]

 static  extern  IntPtr  SendMessage(IntPtr  hWnd, int  Msg, int  wParam, IntPtr  lParam);

 // overloaded SendMessage for strings 

 [DllImport ("user32.dll" , CharSet=CharSet .Auto)]

 static  extern  IntPtr  SendMessage(IntPtr  hWnd, int  Msg, int  wParam, string  lParam);

 [DllImport ("user32.dll" , SetLastError = true , CharSet = CharSet .Auto)]

 static  extern  IntPtr  FindWindowEx(IntPtr  parentHandle, int  childAfter, string  lclassName, int  windowTitle);

 static  void  Main(string [] args)

 {

 System.Diagnostics.Process  OtherProcess = new  System.Diagnostics.Process ();

 OtherProcess.StartInfo.FileName = ProgramLocation;

 OtherProcess.Start();

 OtherProcess.WaitForInputIdle();

 // get the TextBox 

 IntPtr  TextBoxhWnd = GetDlgItem(OtherProcess.MainWindowHandle, TextBoxId);

 Console .WriteLine("Process id: {0:X}; Main window: {1:X}; TextBox {2:X} " , OtherProcess.Id,

 OtherProcess.MainWindowHandle.ToInt32(), TextBoxhWnd.ToInt32());

 // put some text into the TextBox 

 string  text = "some text" ;

 SendMessage(TextBoxhWnd, WM_SETTEXT, 0, text);

 // do a save; we must use PostMessage since SendMessage 

 // would not return until the dialog is closed 

 PostMessage(OtherProcess.MainWindowHandle, WM_COMMAND, FileMenuId, IntPtr .Zero);

 Thread .Sleep(100);

 IntPtr  SaveDialoghWnd = FindSaveAs(OtherProcess.Id);

 if  (SaveDialoghWnd == IntPtr .Zero)

 {

 Console .WriteLine("SaveAs dialog not found" );

 OtherProcess.CloseMainWindow();

 return ;

 }

 Console .WriteLine("Press a key and then the Save As dialog will be canceled" );

 Console .ReadKey();

 // cancel the save. A BN_CLICKED message is sent to the dialog. First the's 

 // window handle is found. 

 IntPtr  CancelButtonhWnd = GetDlgItem(SaveDialoghWnd, CancelButtonId);

 int  wParam = (BN_CLICKED << 16) | (CancelButtonId & 0xffff);

 SendMessage(SaveDialoghWnd, WM_COMMAND, wParam, CancelButtonhWnd);

 Console .WriteLine("Press a key and then Notepad and this program will close" );

 Console .ReadKey();

 OtherProcess.CloseMainWindow();

 }

 /// 
 

 /// Find the Save As dialog. I't kno how reliable this is; this is 

 /// just for demostration purposes. 

 ///  

 /// Process id of the other process 

 /// Window handle for the Save As dialog 

 private  static  IntPtr  FindSaveAs(int  pid)

 {

 IntPtr  SaveDialoghWnd = FindWindowEx(IntPtr .Zero, 0, DialogClass, 0);

 if  (SaveDialoghWnd == IntPtr .Zero)

 return  IntPtr .Zero;

 int  processId;

 GetWindowThreadProcessId(SaveDialoghWnd, out  processId);

 if  (processId != pid)

 return  IntPtr .Zero;

 return  SaveDialoghWnd;

 }

 }

 }