C#

public delegate void ButtonEventHandler(Button sender, EventArgs e);
public class MyPanel : Panel
{
  public MyPanel()
  {
    // Initialize controls.
    button1.Click += new EventHandler(this.button_Click);
    button2.Click += new EventHandler(this.button_Click);
    // ...
  }
 
  public event ButtonEventHandler ButtonClick;
 
  private void button_Click(object sender, EventArgs e)
  {
    if (this.ButtonClick != null)
      this.ButtonClick(sender as Button, e);
  }
}

• As of date, winforms don't (directly) support active documents (ole container). Whidbey due in June is supposed to solve this, but I guess this is too late!
  
• Internet explorer is a ole site for all sorts of things, including active documents. So if you host IE in your form, it can in turn act like a host for whatever OLE document including Word, Excel, ... But showing it is mostly the thing you can do with it. It's much harder to tunnel commands this way.
  
• Although C# does COM interop, it's not very good at doing this, especially when you need both the visible stuff, and the automation stuff. What I mean is that there are a lot of problems when you the stuff to release well from the memory, to behave well when you click, etc.
  

using System.Windows.Forms; // Notice the ;
public class MainForm : Form
{
  // ...
}