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Access violation calling CreateProcess in C#

I am trying to write C# code that, running in an elevated process, creates a non-elevated process. The (only) answer to the SO question How to call CreateProcess() with STARTUPINFOEX from C# and re-parent the child contains ready-to-use code. I copied this code, but instead of creating a process, it throws an AccessViolationException. The exception text Attempted to read or write protected memory. This is often an indication that other memory is corrupt. does not help to identify the culprit, however from low-level debugging I can see that the processor is trying to read from memory at a very small address like 0x00000004 which, of course, goes wrong.
The code, briefly explained, retrieves a handle of the desktop process, then calls InitializeProcThreadAttributeList and UpdateProcThreadAttribute to initialize the respective fields of a STARTUPINFOEX struct which is then passed into the CreateProcess Windows API function. CreateProcess should then create the new process as a child of the desktop process.
This function expects in its 9th parameter a pointer to either a STARTUPINFO or a STARTUPINFOEX (which contains a STATUPINFO at its begin). If it's a STARTUPINFOEX, the 6th parameter should contain the EXTENDED_STARTUPINFO_PRESENT flag.
When I don't pass the EXTENDED_STARTUPINFO_PRESENT flag so that CreateProcess think it's being passed just a STARTUPINFO, all works fine except that the created process is elevated (as is the calling process). However, as soon as I add this flag, the access violation occurs. For hours I have tried modifying parameter attributes etc., but the problem persists. I have the essentially same code running in C++, so I know it can work. What am I doing wrong?
The code below doesn't contain elaborated error checking, but it should compile and demonstrate the problem out of the box.
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
namespace RunNonElevatedCSharp
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
StartNonElevated(#"C:\WINDOWS\system32\cmd.exe", "");
}
public static int StartNonElevated(string strAppPath, string strCommandLine)
{
bool bSuccess = false;
IntPtr hShellProcess = IntPtr.Zero;
var pInfo = new PROCESS_INFORMATION();
var sInfoEx = new STARTUPINFOEX();
sInfoEx.StartupInfo.cb = Marshal.SizeOf(sInfoEx);
try
{
IntPtr hShellWnd = GetShellWindow();
if (hShellWnd == IntPtr.Zero)
{
return 0;
}
UInt32 pid;
if (GetWindowThreadProcessId(hShellWnd, out pid) == 0)
{
return 0;
}
hShellProcess = OpenProcess(PROCESS_CREATE_PROCESS, FALSE, pid);
if (hShellProcess == IntPtr.Zero)
{
return 0;
}
IntPtr nBufferSize = IntPtr.Zero;
InitializeProcThreadAttributeList(IntPtr.Zero, 1, 0, ref nBufferSize);
if (nBufferSize == IntPtr.Zero)
{
return 0;
}
sInfoEx.lpAttributeList = Marshal.AllocHGlobal(nBufferSize);
if (sInfoEx.lpAttributeList == IntPtr.Zero)
{
return 0;
}
if (!InitializeProcThreadAttributeList(sInfoEx.lpAttributeList, 1, 0, ref nBufferSize))
{
return 0;
}
if (!UpdateProcThreadAttribute(sInfoEx.lpAttributeList, 0, (IntPtr)PROC_THREAD_ATTRIBUTE_PARENT_PROCESS, hShellProcess, (IntPtr)IntPtr.Size, IntPtr.Zero, IntPtr.Zero))
{
return 0;
}
// s1 and s2 may not be required
string s1 = "" + strAppPath + "";
string s2 = "";
// The next line causes an access violation unless you remove the 'EXTENDED_STARTUPINFO_PRESENT' flag
if (!CreateProcess(s1, s2, IntPtr.Zero, IntPtr.Zero, false, CREATE_NEW_CONSOLE | EXTENDED_STARTUPINFO_PRESENT | 0,
IntPtr.Zero, null, ref sInfoEx, out pInfo))
{
return 0;
}
bSuccess = true;
CloseHandle(pInfo.hThread);
CloseHandle(pInfo.hProcess);
return pInfo.dwProcessId;
}
finally
{
if (!bSuccess)
{
var lastError = Marshal.GetLastWin32Error();
Debug.WriteLine("Error: " + lastError.ToString());
}
if (sInfoEx.lpAttributeList != IntPtr.Zero)
{
DeleteProcThreadAttributeList(sInfoEx.lpAttributeList);
Marshal.FreeHGlobal(sInfoEx.lpAttributeList);
}
if (hShellProcess != IntPtr.Zero)
CloseHandle(hShellProcess);
}
}
[DllImport("User32.dll", SetLastError = true)]
public static extern IntPtr GetShellWindow();
[DllImport("User32.dll", SetLastError = true)]
public static extern UInt32 GetWindowThreadProcessId(IntPtr hWnd, out UInt32 lpdwProcessId);
[DllImport("Kernel32.dll", SetLastError = true)]
public static extern IntPtr OpenProcess(UInt32 dwDesiredAccess, int bInheritHandle, UInt32 dwProcessId);
[DllImport("kernel32.dll", SetLastError = true)][return: MarshalAs(UnmanagedType.Bool)]
public static extern bool InitializeProcThreadAttributeList(IntPtr lpAttributeList, int dwAttributeCount, int dwFlags, ref IntPtr lpSize);
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool UpdateProcThreadAttribute(IntPtr lpAttributeList, uint dwFlags, IntPtr Attribute, IntPtr lpValue, IntPtr cbSize,
IntPtr lpPreviousValue, IntPtr lpReturnSize);
[DllImport("kernel32.dll", CharSet = CharSet.Unicode, EntryPoint = "CreateProcessW", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool CreateProcess(string lpApplicationName, string lpCommandLine,
[In, Optional] IntPtr lpProcessAttributes, [In, Optional] IntPtr lpThreadAttributes,
bool bInheritHandles, uint dwCreationFlags,
[In, Optional] IntPtr lpEnvironment, [In, Optional] string lpCurrentDirectory,
[In] ref STARTUPINFOEX lpStartupInfo, [Out] out PROCESS_INFORMATION lpProcessInformation);
[DllImport("Kernel32.dll", SetLastError = true)]
public static extern int CloseHandle(IntPtr hObject);
[DllImport("kernel32.dll")]
private static extern void DeleteProcThreadAttributeList(IntPtr lpAttributeList);
public const UInt32 PROCESS_CREATE_PROCESS = 0x0080;
public const int FALSE = 0;
public const int PROC_THREAD_ATTRIBUTE_PARENT_PROCESS = 0x00020000;
public const uint CREATE_NEW_CONSOLE = 0x00000010;
public const uint EXTENDED_STARTUPINFO_PRESENT = 0x00080000;
}
[StructLayout(LayoutKind.Sequential)]
public struct PROCESS_INFORMATION
{
public IntPtr hProcess;
public IntPtr hThread;
public int dwProcessId;
public int dwThreadId;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct STARTUPINFOEX
{
public STARTUPINFO StartupInfo;
public IntPtr lpAttributeList;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct STARTUPINFO
{
public Int32 cb;
public string lpReserved;
public string lpDesktop;
public string lpTitle;
public Int32 dwX;
public Int32 dwY;
public Int32 dwXSize;
public Int32 dwYSize;
public Int32 dwXCountChars;
public Int32 dwYCountChars;
public Int32 dwFillAttribute;
public Int32 dwFlags;
public Int16 wShowWindow;
public Int16 cbReserved2;
public IntPtr lpReserved2;
public IntPtr hStdInput;
public IntPtr hStdOutput;
public IntPtr hStdError;
}
}
When the access violation occurs, the program cannot continue; the "finally" block isn't executed.
Looking forward to any replies...
Hans

Your call to UpdateProcThreadAttribute() is wrong. The 4th parameter needs the address of hShellProcess, not the value. This is even stated as much in this answer to the other question you linked to (the code in the other question has the same bug):
Second, the lpValue parameter of the UpdateProcThreadAttribute function must be a pointer to the attribute value (in your case, parentHandle), not the value itself.
The documentation for PROC_THREAD_ATTRIBUTE_PARENT_PROCESS says:
The lpValue parameter is a pointer to a handle to a process to use instead of the calling process as the parent for the process being created. The process to use must have the PROCESS_CREATE_PROCESS access right.
You said that you copied the other answer's code, but your code does not look like the other answer's code, and certainly does not contain the fix that the other answer had provided.
In your code, change this:
if (!UpdateProcThreadAttribute(..., hShellProcess, ...))
To this:
IntPtr lpValue = IntPtr.Zero;
...
lpValue = Marshal.AllocHGlobal(IntPtr.Size);
Marshal.WriteIntPtr(lpValue, hShellProcess);
if (!UpdateProcThreadAttribute(..., lpValue, ...))
...
Marshal.FreeHGlobal(lpValue);

Hide desktop icons from C# WPF

I need a solution to show/hide desktop icons programmatically with C# WPF
Now one possible way is to change the this registry value:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced
HideIcons = 1
But to make it take effect I need to restart Explorer.exe which is not an option.
Cause my program runs on desktop background. and killing Explorer kills the program and I have restart it.
I also tried this:
Stackoverflow Link
But it didn't work on Windows 10
So, is there any other way to do it? Please Help !

Create Class Library add this code in it
and add namespace System.Runtime.InteropServices
[DllImport("user32.dll", SetLastError = true)]
static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
[DllImport("user32.dll", SetLastError = true)]
static extern IntPtr GetWindow(IntPtr hWnd, GetWindow_Cmd uCmd);
enum GetWindow_Cmd : uint
{
GW_HWNDFIRST = 0,
GW_HWNDLAST = 1,
GW_HWNDNEXT = 2,
GW_HWNDPREV = 3,
GW_OWNER = 4,
GW_CHILD = 5,
GW_ENABLEDPOPUP = 6
}
[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);
private const int WM_COMMAND = 0x111;
public static void ToggleDesktopIcons()
{
var toggleDesktopCommand = new IntPtr(0x7402);
IntPtr hWnd = GetWindow(FindWindow("Progman", "Program Manager"), GetWindow_Cmd.GW_CHILD);
SendMessage(hWnd, WM_COMMAND, toggleDesktopCommand, IntPtr.Zero);
}
[return: MarshalAs(UnmanagedType.Bool)]
[DllImport("user32.dll", SetLastError = true)]
private static extern bool GetWindowInfo(IntPtr hwnd, ref WINDOWINFO pwi);
[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
private int _Left;
private int _Top;
private int _Right;
private int _Bottom;
}
[StructLayout(LayoutKind.Sequential)]
struct WINDOWINFO
{
public uint cbSize;
public RECT rcWindow;
public RECT rcClient;
public uint dwStyle;
public uint dwExStyle;
public uint dwWindowStatus;
public uint cxWindowBorders;
public uint cyWindowBorders;
public ushort atomWindowType;
public ushort wCreatorVersion;
public WINDOWINFO(Boolean? filler)
: this() // Allows automatic initialization of "cbSize" with "new WINDOWINFO(null/true/false)".
{
cbSize = (UInt32)(Marshal.SizeOf(typeof(WINDOWINFO)));
}
}
public static bool IsVisible()
{
IntPtr hWnd = GetWindow(GetWindow(FindWindow("Progman", "Program Manager"), GetWindow_Cmd.GW_CHILD), GetWindow_Cmd.GW_CHILD);
WINDOWINFO info = new WINDOWINFO();
info.cbSize = (uint)Marshal.SizeOf(info);
GetWindowInfo(hWnd, ref info);
return (info.dwStyle & 0x10000000) == 0x10000000;
}
add this dll reference to your project..
and call dllClass_name.ToggleDesktopIcon();

Hook up click event after AppendMenu of 3rd party Application

i'm trying to add a new MenuItem using DLL Fucntions imported of the user32.dll using DLLImort to a third party application out of my WPF app.
No I'd like to get the click event of the newly generated MenuItem. Any ideas?
Here's the code so far. I know there are functions of SetWindowHookEx or something else, but I'm stuck.
It's some test code and not bulletproofed..
public partial class MainWindow : Window
{
[DllImport("user32.dll")]
private static extern IntPtr GetMenu(IntPtr hWnd);
[DllImport("user32.dll")]
private static extern IntPtr GetSubMenu(IntPtr hMenu, int nPos);
[DllImport("user32.dll")]
private static extern int GetMenuItemCount(IntPtr hMenu);
[DllImport("user32.dll")]
private static extern bool InsertMenuItem(IntPtr hMenu, uint uItem, bool
fByPosition, [In] ref MENUITEMINFO lpmii);
[DllImport("user32.dll")]
private static extern bool DrawMenuBar(IntPtr hWnd);
internal const UInt32 MIIM_FTYPE = 0x00000100;
internal const UInt32 MF_STRING = 0x00000000;
internal const UInt32 MF_OWNERDRAW = 0x00000100;
const uint MF_POPUP = 0x00000010;
[DllImport("user32.dll", CharSet = CharSet.Auto)]
static extern bool AppendMenu(IntPtr hMenu, MenuFlags uFlags, uint uIDNewItem, string lpNewItem);
[DllImport("user32.dll")]
static extern IntPtr CreatePopupMenu();
[Flags]
public enum MenuFlags : uint
{
MF_STRING = 0,
MF_BYPOSITION = 0x400,
MF_SEPARATOR = 0x800,
MF_REMOVE = 0x1000,
MF_POPUP = 0x00000010,
}
[StructLayout(LayoutKind.Sequential)]
struct MENUITEMINFO
{
public uint cbSize;
public uint fMask;
public uint fType;
public uint fState;
public uint wID;
public IntPtr hSubMenu;
public IntPtr hbmpChecked;
public IntPtr hbmpUnchecked;
public IntPtr dwItemData;
public string dwTypeData;
public uint cch;
public IntPtr hbmpItem;
// return the size of the structure
public static uint sizeOf
{
get { return (uint)Marshal.SizeOf(typeof(MENUITEMINFO)); }
}
}
public MainWindow()
{
InitializeComponent();
Loaded += OnLoaded;
}
private void OnLoaded(object sender, RoutedEventArgs e)
{
createMenuEntry();
}
private void createMenuEntry()
{
Process[] proceses = Process.GetProcessesByName("spotify");
Process process = proceses.Where(e => e.MainWindowTitle == "Spotify").First();
IntPtr handle = process.MainWindowHandle;
IntPtr mainMenu = GetMenu(handle);
int mainMenuItemCount = GetMenuItemCount(mainMenu);
AppendMenu(mainMenu, MenuFlags.MF_STRING, 555, "TestEntry");
}
protected override void OnSourceInitialized(EventArgs e)
{
base.OnSourceInitialized(e);
//HwndSource source = PresentationSource.FromVisual(this) as HwndSource;
//source.AddHook(WndProc);
}
private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
// Handle messages...
Debug.WriteLine((int)wParam);
if (((int)wParam == 555))
{
MessageBox.Show("Click");
}
return IntPtr.Zero;
}
}
Thanks for any ideas or suggestions in advance.

Your first step is to put down the C# and understand how the native menu API works. Start here: https://msdn.microsoft.com/en-us/library/windows/desktop/ms647553.aspx
I strongly recommend that you create a new C++ project and write a simple program to add a menu and respond to clicks.
The key information is found in the documentation I linked to, with my emphasis:
When the user chooses a command item, the system sends a command message to the window that owns the menu. If the command item is on the window menu, the system sends the WM_SYSCOMMAND message. Otherwise, it sends the WM_COMMAND message.
You need to intercept that message. I suspect that means to need to use a global WH_CALLWNDPROC hook. That's going to need an unmanaged DLL to implement the hook.

CreateWindowEx and RegisterClass C#

I want to create a new class and then show a window with the specefied class.
I wrote following codes for that :
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
[DllImport("user32.dll")]
static extern bool UpdateWindow(IntPtr hWnd);
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
[DllImport("user32.dll", SetLastError = true, EntryPoint = "CreateWindowEx")]
public static extern IntPtr CreateWindowEx(
int dwExStyle,
string lpClassName,
string lpWindowName,
int dwStyle,
int x,
int y,
int nWidth,
int nHeight,
IntPtr hWndParent,
IntPtr hMenu,
IntPtr hInstance,
IntPtr lpParam);
[System.Runtime.InteropServices.DllImport("user32.dll", SetLastError = true)]
static extern System.UInt16 RegisterClassW(
[System.Runtime.InteropServices.In] ref WNDCLASSEX lpWndClass
);
struct WNDCLASSEX
{
[MarshalAs(UnmanagedType.U4)]
public int cbSize;
[MarshalAs(UnmanagedType.U4)]
public int style;
public IntPtr lpfnWndProc; // not WndProc
public int cbClsExtra;
public int cbWndExtra;
public IntPtr hInstance;
public IntPtr hIcon;
public IntPtr hCursor;
public IntPtr hbrBackground;
public string lpszMenuName;
public string lpszClassName;
public IntPtr hIconSm;
}
[DllImport("user32.dll")]
static extern IntPtr DefWindowProc(IntPtr hWnd, uint uMsg, IntPtr wParam, IntPtr lParam);
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
WNDCLASSEX wind_class = new WNDCLASSEX();
wind_class.cbSize = Marshal.SizeOf(typeof(WNDCLASSEX));
wind_class.style = 0x00020000;
wind_class.hbrBackground = (IntPtr) 5;
wind_class.cbClsExtra = 0;
wind_class.cbWndExtra = 0;
wind_class.hInstance = Marshal.GetHINSTANCE(GetType().Module);
wind_class.hIcon = this.Icon.Handle;
wind_class.hCursor = IntPtr.Zero;
wind_class.lpszMenuName = string.Empty;
wind_class.lpszClassName = "MyClass";
wind_class.lpfnWndProc = DefWindowProc(IntPtr.Zero, 0, IntPtr.Zero, IntPtr.Zero);
RegisterClassW(ref wind_class);
IntPtr lolo = CreateWindowEx(0, "MyClass", "MyClass",0,0,0,30,40,IntPtr.Zero,IntPtr.Zero,IntPtr.Zero,IntPtr.Zero);
ShowWindow(lolo, 1);
UpdateWindow(lolo);
}
}
}
But it isn't working correctly.
It doesn't show the window. when i search with Spy++ by my class name , It cant find any results..
I searched in web and do some edits in my code but they didn't work.
Where is my Problem !?
Regards.

Plain-vanilla Win32 is no fun from Win32 C, and it is much less fun from .NET. But anyway, it may be useful in rare cases. Here comes a C# class which should do what you want.
First, a general remarks on your software. In Win32, you should always check the return codes of the system calls, and in case of an error, call GetLastError() to get a more detailed information about the failure. If you had checked the result of the RegisterClass function and it failed, you would have known that it is useless to continue without having fixed that one.
The following is a class which may be used as template for further studies and which should successfully register and create a resizable window. Additionally some simple actions like doubleclick are processed in a custom Window procedure. For some parts of the code credit goes to this site being one of the very few I found in the web presenting something working.
The CreateWindowEx is tricky, because you must NOT put in a string as class name, but the result of the RegisterClassEx. The used constants are found mainly in the C-header file winuser.h. To be able to do something useful with this method, the main painting has to be done "by hand", being a cumbersome and tedious work by manipulationg Device Contexts properly. Of course, all this does not show up in the following example. The "create" method of the class may be called e.g. from a Windows Form button click. The namespace name is of course arbitrarily selected. The WinForm project is x86 32-bit, .NET 4.0.
Have fun!
namespace Win32FromForms
{
delegate IntPtr WndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);
class Win32Window
{
const UInt32 WS_OVERLAPPEDWINDOW = 0xcf0000;
const UInt32 WS_VISIBLE = 0x10000000;
const UInt32 CS_USEDEFAULT = 0x80000000;
const UInt32 CS_DBLCLKS = 8;
const UInt32 CS_VREDRAW = 1;
const UInt32 CS_HREDRAW = 2;
const UInt32 COLOR_WINDOW = 5;
const UInt32 COLOR_BACKGROUND = 1;
const UInt32 IDC_CROSS = 32515;
const UInt32 WM_DESTROY = 2;
const UInt32 WM_PAINT = 0x0f;
const UInt32 WM_LBUTTONUP = 0x0202;
const UInt32 WM_LBUTTONDBLCLK = 0x0203;
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
struct WNDCLASSEX
{
[MarshalAs(UnmanagedType.U4)]
public int cbSize;
[MarshalAs(UnmanagedType.U4)]
public int style;
public IntPtr lpfnWndProc;
public int cbClsExtra;
public int cbWndExtra;
public IntPtr hInstance;
public IntPtr hIcon;
public IntPtr hCursor;
public IntPtr hbrBackground;
public string lpszMenuName;
public string lpszClassName;
public IntPtr hIconSm;
}
private WndProc delegWndProc = myWndProc;
[DllImport("user32.dll")]
static extern bool UpdateWindow(IntPtr hWnd);
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
[System.Runtime.InteropServices.DllImport("user32.dll", SetLastError = true)]
static extern bool DestroyWindow(IntPtr hWnd);
[DllImport("user32.dll", SetLastError = true, EntryPoint = "CreateWindowEx")]
public static extern IntPtr CreateWindowEx(
int dwExStyle,
UInt16 regResult,
//string lpClassName,
string lpWindowName,
UInt32 dwStyle,
int x,
int y,
int nWidth,
int nHeight,
IntPtr hWndParent,
IntPtr hMenu,
IntPtr hInstance,
IntPtr lpParam);
[DllImport("user32.dll", SetLastError = true, EntryPoint = "RegisterClassEx")]
static extern System.UInt16 RegisterClassEx([In] ref WNDCLASSEX lpWndClass);
[DllImport("kernel32.dll")]
static extern uint GetLastError();
[DllImport("user32.dll")]
static extern IntPtr DefWindowProc(IntPtr hWnd, uint uMsg, IntPtr wParam, IntPtr lParam);
[DllImport("user32.dll")]
static extern void PostQuitMessage(int nExitCode);
//[DllImport("user32.dll")]
//static extern sbyte GetMessage(out MSG lpMsg, IntPtr hWnd, uint wMsgFilterMin,
// uint wMsgFilterMax);
[DllImport("user32.dll")]
static extern IntPtr LoadCursor(IntPtr hInstance, int lpCursorName);
[DllImport("user32.dll")]
static extern bool TranslateMessage([In] ref MSG lpMsg);
[DllImport("user32.dll")]
static extern IntPtr DispatchMessage([In] ref MSG lpmsg);
internal bool create()
{
WNDCLASSEX wind_class = new WNDCLASSEX();
wind_class.cbSize = Marshal.SizeOf(typeof(WNDCLASSEX));
wind_class.style = (int)(CS_HREDRAW | CS_VREDRAW | CS_DBLCLKS ) ; //Doubleclicks are active
wind_class.hbrBackground = (IntPtr) COLOR_BACKGROUND +1 ; //Black background, +1 is necessary
wind_class.cbClsExtra = 0;
wind_class.cbWndExtra = 0;
wind_class.hInstance = Marshal.GetHINSTANCE(this.GetType().Module); ;// alternative: Process.GetCurrentProcess().Handle;
wind_class.hIcon = IntPtr.Zero;
wind_class.hCursor = LoadCursor(IntPtr.Zero, (int)IDC_CROSS);// Crosshair cursor;
wind_class.lpszMenuName = null;
wind_class.lpszClassName = "myClass";
wind_class.lpfnWndProc = Marshal.GetFunctionPointerForDelegate(delegWndProc);
wind_class.hIconSm = IntPtr.Zero;
ushort regResult = RegisterClassEx(ref wind_class);
if (regResult == 0)
{
uint error = GetLastError();
return false;
}
string wndClass = wind_class.lpszClassName;
//The next line did NOT work with me! When searching the web, the reason seems to be unclear!
//It resulted in a zero hWnd, but GetLastError resulted in zero (i.e. no error) as well !!??)
//IntPtr hWnd = CreateWindowEx(0, wind_class.lpszClassName, "MyWnd", WS_OVERLAPPEDWINDOW | WS_VISIBLE, 0, 0, 30, 40, IntPtr.Zero, IntPtr.Zero, wind_class.hInstance, IntPtr.Zero);
//This version worked and resulted in a non-zero hWnd
IntPtr hWnd = CreateWindowEx(0, regResult, "Hello Win32", WS_OVERLAPPEDWINDOW | WS_VISIBLE, 0, 0, 300, 400, IntPtr.Zero, IntPtr.Zero, wind_class.hInstance, IntPtr.Zero);
if (hWnd == ((IntPtr)0))
{
uint error = GetLastError();
return false;
}
ShowWindow(hWnd, 1);
UpdateWindow(hWnd);
return true;
//The explicit message pump is not necessary, messages are obviously dispatched by the framework.
//However, if the while loop is implemented, the functions are called... Windows mysteries...
//MSG msg;
//while (GetMessage(out msg, IntPtr.Zero, 0, 0) != 0)
//{
// TranslateMessage(ref msg);
// DispatchMessage(ref msg);
//}
}
private static IntPtr myWndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam)
{
switch (msg)
{
// All GUI painting must be done here
case WM_PAINT:
break;
case WM_LBUTTONDBLCLK :
MessageBox.Show("Doubleclick");
break;
case WM_DESTROY:
DestroyWindow(hWnd);
//If you want to shutdown the application, call the next function instead of DestroyWindow
//PostQuitMessage(0);
break;
default:
break;
}
return DefWindowProc(hWnd, msg, wParam, lParam);
}
}
}

The problem is the marshaling of strings to LPStr, if you do it like this then the class name works:
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
struct WNDCLASSEX
{
[MarshalAs(UnmanagedType.U4)]
public int cbSize;
[MarshalAs(UnmanagedType.U4)]
public int style;
public IntPtr lpfnWndProc;
public int cbClsExtra;
public int cbWndExtra;
public IntPtr hInstance;
public IntPtr hIcon;
public IntPtr hCursor;
public IntPtr hbrBackground;
[MarshalAs(UnmanagedType.LPStr)]
public string lpszMenuName;
[MarshalAs(UnmanagedType.LPStr)]
public string lpszClassName;
public IntPtr hIconSm;
}
[DllImport("user32.dll", SetLastError = true, EntryPoint = "CreateWindowEx")]
public static extern IntPtr CreateWindowEx(
int dwExStyle,
//UInt16 regResult,
[MarshalAs(UnmanagedType.LPStr)]
string lpClassName,
[MarshalAs(UnmanagedType.LPStr)]
string lpWindowName,
UInt32 dwStyle,
int x,
int y,
int nWidth,
int nHeight,
IntPtr hWndParent,
IntPtr hMenu,
IntPtr hInstance,
IntPtr lpParam);

C# and partially working SendMessage?

I've tried to send text messages to various applications in Windows 7 (eg. Notepad++, Notepad etc.). SendMessage is working fine for Notepad but not for Notepad++.
If i'm sending text to Notepad everything appears fine, whole text and i'm getting 1 as return from SendMessage method. But for Notepad++ only first letter appears and method SendMessage is returning 0, however Marshal.GetLastWin32Error() is not returning any error (result 0)?
Here's the code:
GUITHREADINFO gti = new GUITHREADINFO();
IntPtr hWnd = GetForegroundWindow();
uint processId;
uint activeThreadId = GetWindowThreadProcessId(hWnd, out processId);
if (GetInfo(activeThreadId, out gti))
{
int EM_REPLACESEL = 0x00C2;
int error = Marshal.GetLastWin32Error();
int result = SendMessageW(gti.hwndCaret, EM_REPLACESEL, -1, passed);//3rd param doesn't change anything
error = Marshal.GetLastWin32Error();
}
WinAPI functions and GetInfo method as long with required structures are defined as:
[DllImport("User32.dll", EntryPoint = "SendMessageW", SetLastError = true, CharSet = CharSet.Unicode)]
public static extern int SendMessageW(IntPtr hWnd, int uMsg, int wParam, string lParam);
[DllImport("user32.dll")]
static extern IntPtr GetForegroundWindow();
[DllImport("user32.dll", SetLastError = true)]
static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);
//"Borrowed" code
public static bool GetInfo(uint hwnd, out GUITHREADINFO lpgui)
{
uint lpdwProcessId;
uint threadId = GetWindowThreadProcessId(hwnd, out lpdwProcessId);
lpgui = new GUITHREADINFO();
lpgui.cbSize = Marshal.SizeOf(lpgui);
return GetGUIThreadInfo(threadId, ref lpgui);
}
[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
public int iLeft;
public int iTop;
public int iRight;
public int iBottom;
}
[StructLayout(LayoutKind.Sequential)]
public struct GUITHREADINFO
{
public int cbSize;
public int flags;
public IntPtr hwndActive;
public IntPtr hwndFocus;
public IntPtr hwndCapture;
public IntPtr hwndMenuOwner;
public IntPtr hwndMoveSize;
public IntPtr hwndCaret;
public RECT rectCaret;
}
So well i wonder what should i do to fix it so it would work (fully) for all windows not only for edit control in Notepad?