Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Windows.Forms.Document.InsertString(LineTag tag, Int32 pos, String s) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextControl.cs:line 2167
   at System.Windows.Forms.Document.Insert(Line line, LineTag tag, Int32 pos, Boolean update_caret, String s) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextControl.cs:line 2126
   at System.Windows.Forms.Document.ReplaceSelection(String s) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextControl.cs:line 3350
   at System.Windows.Forms.TextBoxBase.set_SelectedText(String value) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextBoxBase.cs:line 437
   at System.Windows.Forms.TextBoxBase.Paste(IDataObject clip, Format format, Boolean obey_length) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextBoxBase.cs:line 1851
   at System.Windows.Forms.TextBoxBase.ProcessKey(Keys keyData) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextBoxBase.cs:line 1046
   at System.Windows.Forms.TextBoxBase.WndProc(Message& m) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextBoxBase.cs:line 1213
   at System.Windows.Forms.TextBox.WndProc(Message& m) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TextBox.cs:line 264
   at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) in d:\linux\matrix\mono\mcs\class\managed.windows.forms\system.windows.forms\control.cs:line 166
   at System.Windows.Forms.NativeWindow.WndProc(IntPtr hWnd, Msg msg, IntPtr wParam, IntPtr lParam) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\NativeWindow.cs:line 159
   at System.Windows.Forms.XplatUIWin32.Win32DispatchMessage(MSG& msg)
   at System.Windows.Forms.XplatUIWin32.DispatchMessage(MSG& msg) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\XplatUIWin32.cs:line 1500
   at System.Windows.Forms.XplatUI.DispatchMessage(MSG& msg) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\XplatUI.cs:line 428
   at System.Windows.Forms.Application.RunLoop(Boolean Modal, ApplicationContext context) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\Application.cs:line 530
   at System.Windows.Forms.Application.Run(Form mainForm) in D:\linux\matrix\mono\mcs\class\Managed.Windows.Forms\System.Windows.Forms\Application.cs:line 421
   at TextBoxScroll.MainForm.Main(String[] args) in d:\linux\bugs\79580\test79580\form1.cs:line 21The program '[2592] Test79580.exe' has exited with code 0 (0x0).