looking for a comprehensive version of most common API functions used in
.Net, sample below:

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using System;
using System.Runtime.InteropServices;

namespace ApiWrapper
{
/// <summary>
/// Summary description for Win32API.
/// Date: 5 March, 2004
/// </summary>
public class Win32API
{
 /// <summary>
 /// The SendMessage function sends the specified message to a window or
windows.
 /// The function calls the window procedure for the specified window and
does not return
 /// until the window procedure has processed the message. The PostMessage
function, in contrast,
 /// posts a message to a thread's message queue and returns immediately.
 /// </summary>
 /// <param name="WindowHandle">hWnd: Identifies the window whose window
procedure is to receive
 /// the message. Two values have special meanings:
 /// HWND_BROADCAST
 ///  The message is posted to all top-level windows in the system,
including disabled or
 ///  invisible unowned windows, overlapped windows, and pop-up windows.
 ///  The message is not posted to child windows.
 /// NULL
 ///  The function behaves like a call to PostThreadMessage with the
dwThreadId parameter set
 ///  to the identifier of the current thread.</param>
 /// <param name="Command">wMsg: Message to send</param>
 /// <param name="Data">wParam: Specifies additional message-specific
information.</param>
 /// <param name="ID">lParam: Specifies additional message-specific
information.</param>
 /// <returns>The return value specifies the result of the message
processing and depends on the message sent.</returns>
 [DllImport("user32.dll", EntryPoint="SendMessage")]
 public static extern int SendMessage(int WindowHandle, int Command, int
Data, int ID);

 /// <summary>
 /// The PostMessage function places (posts) a message in the message queue
associated with the
 /// thread that created the specified window and then returns without
waiting for the thread
 /// to process the message.
 /// </summary>
 /// <param name="WindowHandle">hWnd: Identifies the window whose window
procedure is to receive
 /// the message. Two values have special meanings:
 /// HWND_BROADCAST
 ///  The message is posted to all top-level windows in the system,
including disabled or
 ///  invisible unowned windows, overlapped windows, and pop-up windows.
 ///  The message is not posted to child windows.
 /// NULL
 ///  The function behaves like a call to PostThreadMessage with the
dwThreadId parameter set
 ///  to the identifier of the current thread.</param>
 /// <param name="Command">wMsg: Message to send</param>
 /// <param name="Data">wParam: Specifies additional message-specific
information.</param>
 /// <param name="ID">lParam: Specifies additional message-specific
information.</param>
 /// <returns>The return value specifies the result of the message
processing and depends on the message sent.</returns>
 [DllImport("user32.dll", EntryPoint="PostMessage")]
 public static extern int PostMessage(int WindowHandle, int Command, int
Data, int ID);

 /// <summary>
 /// The FindWindow function retrieves the handle to the top-level window
whose class name and
 /// window name match the specified strings. This function does not search
child windows.
 /// </summary>
 /// <param name="ClassName"></param>
 /// <param name="WindowName"></param>
 /// <returns></returns>
 [DllImport("user32.dll", EntryPoint="FindWindow")]
 public static extern int FindWindow(string ClassName, string WindowName);

 [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
 public static extern bool BitBlt(
  IntPtr hdcDest, // handle to destination DC
  int nXDest, // x-coord of destination upper-left corner
  int nYDest, // y-coord of destination upper-left corner
  int nWidth, // width of destination rectangle
  int nHeight, // height of destination rectangle
  IntPtr hdcSrc, // handle to source DC
  int nXSrc, // x-coordinate of source upper-left corner
  int nYSrc, // y-coordinate of source upper-left corner
  System.Int32 dwRop // raster operation code
  );
}
}
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TIA

- sci