//We'll need to import the System.Diagnostics library so we can access the Process class. 
			
			

			using System.Diagnostics; 
			
			

			 
			
			

			//These methods are imported in from the user32.dll. I recommend putting them in a separate class under the same 
			
			

			//namespace in order to avoid cluttering up your code. 
			
			

			[DllImport("user32.dll")] 
			
			

			 public static extern IntPtr FindWindowEx(IntPtr parentHandle, IntPtr childAfter, string className, IntPtr windowTitle); 
			
			

			
			
			

			[DllImport("user32.dll", SetLastError = true)] 
			
			

			public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow); 
			
			

			 
			
			

			[DllImport("user32.dll")] 
			
			

			public static extern int SendMessage(IntPtr hWnd, uint Msg, int wParam, IntPtr lParam); 
			
			

			 
			
			

			[DllImport("user32.dll")] public static extern int SendMessage(IntPtr hWnd, uint Msg, int wParam, StringBuilder lParam); 
			
			

			 
			
			

			[DllImport("user32.dll")] public static extern uint SendMessage(IntPtr hWnd, uint MSG, uint zero, byte[] text); 
			
			

			 
			
			

			[DllImport("user32.dll")] public static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, int wParam, int lParam); 
			
			

			
			
			

			/// Win32 SDK constants 
			
			

			/// </summary> 
			
			

			public const uint WM_SETTEXT = 0x000C; 
			
			

			public const uint WM_GETTEXT = 0x000D; 
			
			

			public const uint EM_SETSEL = 0x000000B1; 
			
			

			public const uint WM_GETTEXTLENGTH = 0x000E; 
			
			

			public const uint SMTO_ABORTIFHUNG = 0x0002; 
			
			

			public const int BM_CLICK = 0x00F5; 
			
			

			 
			
			

			//We will call this method whenever we want to send a message to Yahoo Messenger from our application 
			
			

			public void PostToMessengerChat() 
			
			

			{ 
			
			

			//you can find the name of the process that owns the windows you are trying to access by 
			
			

			//accessing the task-manager. Then load a process array with the following line. 
			
			

			Process[] processes = Process.GetProcessesByName("YahooMessenger"); 
			
			

			//Declare a null window handle called hwnd. 
			
			

			IntPtr hwnd = IntPtr.Zero; 
			
			

			//Declare a null window handle called mainHand 
			
			

			IntPtr mainHand = IntPtr.Zero; 
			
			

			//Iterate through the process array until we find the window we want 
			
			

			foreach (Process p in processes) 
			
			

			{ 
			
			

			//get WindowTitle and check it's the one you want 
			
			

			String checkString = p.MainWindowTitle; 
			
			

			//all !Yahoo chat rooms end with this patternString 
			
			

			String patternString = "-- Chat"; 
			
			

			 
			
			

			if (checkString.Contains(patternString)) 
			
			

			{ 
			
			

			//the pattern matches ! This is the window we want. Get it's handle. 
			
			

			mainHand = p.MainWindowHandle; 
			
			

			} 
			
			

			} 
			
			

			//find the class name of the child window using spy++ (YIMInputWindow) 
			
			

			//this function returns the handle of the window that matches the class name string. 
			
			

			IntPtr childWindow = Win32API.FindWindowEx(mainHand, IntPtr.Zero, "YIMInputWindow", IntPtr.Zero); 
			
			

			
			
			

			//WM_GETTEXTLENGTH - get the length of the users text in the text input window text if there is any 
			
			

			int textLength = Win32API.SendMessage(childWindow, Win32API.WM_GETTEXTLENGTH, 0, IntPtr.Zero); 
			
			

			
			
			

			//create a StringBuilder to hold users text input StringBuilders are {Zero Based} 
			
			

			StringBuilder writingtext = new StringBuilder(textLength + 1); 
			
			

			//WM_GETTEXT - sendmessage with a stringbuilder arg and length arg returns a stringbuilder that contains the 
			
			

			//current text in the YIMInputWindow. This is, so that when we send our message it doesnt mess up the current 
			
			

			//users text if they happen to be typing. This part is a bit weird because the method loads the stringbuilder 
			
			

			//yet we never assign it. By passing the stringbuilder to this method our result is a stringbuilder containing 
			
			

			//the users current text. 
			
			

			Win32API.SendMessage(childWindow, Win32API.WM_GETTEXT, textLength + 1, writingtext); 
			
			

			 
			
			

			//create a byte array of the string we will be sending, in this case it is the currently playing MP3. 
			
			

			byte[] encryptedText_byte = System.Text.Encoding.ASCII.GetBytes((": hears: " + 
			
			

			playList.Items[currentSongNumber]).ToCharArray()); 
			
			

			 
			
			

			//WM_SETTEXT - send our song string byteArray 
			
			

			Win32API.SendMessage(childWindow, Win32API.WM_SETTEXT, 0, encryptedText_byte); 
			
			

			//find the send buttons window handle 
			
			

			IntPtr buttonWindow = Win32API.FindWindowEx(mainHand, IntPtr.Zero, "Button", "&Send"); 
			
			

			//BM_CLICK - click the button to send the song message to the chat 
			
			

			Win32API.SendMessage(buttonWindow, Win32API.BM_CLICK, 0, encryptedText_byte); 
			
			

			
			
			

			//WM_SETTEXT - put the users current text back to it's original place 
			
			

			encryptedText_byte = System.Text.Encoding.ASCII.GetBytes((writingtext.ToString()).ToCharArray()); 
			
			

			Win32API.SendMessage(childWindow, Win32API.WM_SETTEXT, 0, encryptedText_byte); 
			
			

			//WM_SETSEL - put the cursor at the end of the users text so they can keep typing 
			
			

			Win32API.SendMessage(childWindow, Win32API.EM_SETSEL, writingtext.Length, writingtext.Length); 
			
			

			}