Onchanged c# appending form

Question

I am trying to append textbox everytime there is a change in my log text file in c#.

Below is my code but I cant seem to do it. it keep tells me that access to textbox component in main form from another thread c#

public Form1()
{

    InitializeComponent();

    string currentPath = System.Environment.CurrentDirectory;


    FileSystemWatcher watcher = new FileSystemWatcher();
    watcher.Path = currentPath;
    watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
                           | NotifyFilters.FileName | NotifyFilters.DirectoryName;
    watcher.Filter = "*.*";
    watcher.Changed += new FileSystemEventHandler(OnChanged);
    watcher.EnableRaisingEvents = true;






}

private void OnChanged(object source, FileSystemEventArgs e)
{
    textBox1.AppendText("hello ah");
}

Answer 1

FileSystemWatcher delivers events on a different thread, you will have to marshall the AppendText calls to the UI dispatcher:

textBox1.Dispatcher.BeginInvoke(new Action(() =>
      {
          textBox1.AppendText("hello ah");
      }));