Windows GUI Hacking with C#

NativeControl.cs

using System;
using System.Runtime.InteropServices;
using System.Text;

public class NativeControl {

	public readonly IntPtr Handle;

	public string Text {
		get {
			int length = GetWindowTextLength(Handle);
			StringBuilder sb = new StringBuilder(length + 1);
			GetWindowText(Handle, sb, sb.Capacity);
			return sb.ToString();
		}
		set {
			SetWindowText(Handle, value);
		}
	}

	private NativeControl(IntPtr hwnd) {
		Handle = hwnd;
	}

	public static NativeControl FromHandle(IntPtr hwnd) {
		return new NativeControl(hwnd);
	}

	// Native Imports
	[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
	static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString, int nMaxCount);

	[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
	static extern int GetWindowTextLength(IntPtr hWnd);

	[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
	public static extern bool SetWindowText(IntPtr hwnd, String lpString);
}

Program.cs

using System;
using System.Diagnostics;
using System.Drawing;
using System.Runtime.InteropServices;

class Program {

	[DllImport("user32.dll")]
	static extern IntPtr WindowFromPoint(Point p);

	static void Main(string[] args) {
		using(var p = Process.GetProcessesByName("notepad++")[0]) {
			var hwnd = p.MainWindowHandle;
			var x =  NativeControl.FromHandle(hwnd);
			x.Text = "Enjoy Hacking";
		}
	}
	
}