C#

ToolStripItem[] newitems = new ToolStripItem[myToolStripMenuItem.DropDownItems.Count];
myToolStripMenuItem.DropDownItems.CopyTo(newitems, 0);
myToolStripDropDownButton.DropDownItems.AddRange(newitems);

public partial class Form1 : Form
{
  IServiceContainer isc;
  DesignSurface ds;
  IDesignerHost idh;
  ISelectionService iss;  
  IToolboxUser itu;  
  MyToolBox toolbox;

  public Form1()
  {
   // Create the DesignSurface and load it with a form   
   isc = new ServiceContainer();
   ds = new DesignSurface(isc);   
   ds.BeginLoad(typeof(Form));

   idh = (IDesignerHost)ds.GetService(typeof(IDesignerHost));
   iss = (ISelectionService)ds.GetService(typeof(ISelectionService));
   itu = (IToolboxUser)idh.GetDesigner(idh.RootComponent);   
   
   InitializeComponent();

   iss.SelectionChanged += new EventHandler(iss_SelectionChanged);
  }

  private void Form1_Load(object sender, EventArgs e)
  {
   toolbox = new MyToolBox();
   toolbox.Dock = DockStyle.Fill;
   splitContainer1.Panel1.Controls.Add(toolbox);
   isc.AddService(typeof(IToolboxService), toolbox);

   // Get the View of the DesignSurface, host it in a form, and show it
   Control c = ds.View as Control;
   c.Parent = this.splitContainer2.Panel1;
   c.Dock = DockStyle.Fill;
  }

  private void iss_SelectionChanged(object sender, EventArgs e)
  {
   propertyGrid1.SelectedObject = iss.PrimarySelection;
  }
}