C#

private void myFileSystemWatcher_Changed(object sender, FileSystemEventArgs e)
{
  ThreadPool.QueueUserWorkItem(new WaitCallback(DoFileDiff), e.FullPath);
}
private void DoFileDiff(object state)
{
  string path = state as string;
 
  // Diff the file contents with another in a cache or DB - just an exmaple.
  int changedLines = Diff(path);
 
  // Now lets say you need to sync in order to write to a log file, you
  // can use the lock keyword in C# against an object. So long as the object
  // is the same object that you lock against in other methods you want
  // synchronized with each other, it will work (it is a Moniter).
  lock (this)
    WriteToLog(path, "Changed", changedLines);
}

// Declare the delegate as a nested delegate or stand-alone.
// In our case, the <code>WaitCallback</code> that we used earlier is
// already defined, so we'll just use that. The line below is only an
// example of how the WaitCallback is defined:
// public delegate void WaitCallback(object state);
 
private void myFileSystemWatcher_Changed(object sender, FileSystemEventArgs e)
{
  WaitCallback callback = new WaitCallback(DoFileDiff);
  callback.BeginInvoke(e.FullPath, null, null);
}

Monitor.Enter(syncRoot);
try
{
  // The body in the "lock" block would go here.
}
finally
{
  // This always executes whether or not an exception is thrown and
  // makes sure that resources are not locked indefinitely.
  Monitor.Exit();
}

object o = new TreeNode();
// Writes "System.Windows.Forms.TreeNode" to the console window:
Console.WriteLine(o.GetType().FullName);

prpSkinProps.SelectedObject = (e.Node as TreeNodePtr).SkinObject;

propertyGrid.SelectedObject = ((TreeNodePtr)e.Node).SkinObject;

Type t - e.Node.GetType()

if (e.Node is SkinObject)
{
  // ...
}

1. Enter
2. GotFocus
3. Leave
4. Validating
5. Validated
6. LosFocus

1. Enter
2. GotFocus
3. LostFocus
4. Leave
5. Validating
6. Validated

// Hook-up event handlers.
myTextBox.Enter += new EventHandler(myTextBox_Enter);
myTextBox.Leave += new EventHandler(myTextBox_Leave);
myTextBox.LostFocus += new EventHandler(myTextBox_LostFocus);

// Handle events.
private void myTextBox_Enter(object sender, EventArgs e)
{
  myTextBox.TextAlign = HorizontalAlignment.Left;
}
private void myTextBox_Leave(object sender, EventArgs e)
{
  if (Control.MouseButtons != MouseButtons.None)
    myTextBox.TextAlign = HorizontalAlignment.Right;
}
private void myTextBox_LostFocus(object sender, EventArgs e)
{
  if (Control.MouseButtons == MouseButtons.None)
    myTextBox.TextAlign = HorizontalAlignment.Right;
}