This is a little code that allows you to send message to a backgrounded application. To send the “A” char for example, simply call sendKeystroke(Keys.A), and don’t forget to use namespace System.windows.forms to be able to use the Keys object.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace keybound
{
class WindowHook
{
[DllImport("user32.dll")]
public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
[DllImport("user32.dll")]
public static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);
[DllImport("user32.dll")]
public static extern IntPtr PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);
public static void sendKeystroke(ushort k)
{
const uint WM_KEYDOWN = 0x100;
const uint WM_SYSCOMMAND = 0x018;
const uint SC_CLOSE = 0x053;
IntPtr WindowToFind = FindWindow(null, "Untitled1 - Notepad++");
IntPtr result3 = SendMessage(WindowToFind, WM_KEYDOWN, ((IntPtr)k), (IntPtr)0);
//IntPtr result3 = SendMessage(WindowToFind, WM_KEYUP, ((IntPtr)c), (IntPtr)0);
}
}
}