C#

<br />
public partial class MyForm<br />
{<br />
   // Your delegate definition.  It basically defines the prototype of the method.<br />
   delegate void AddItemDelegate(string text);<br />
<br />
   // Method for adding a single item to your list<br />
   private void AddItem(string text)<br />
   {<br />
       if (InvokeRequired)<br />
       {<br />
           // We're not in the UI thread, so we need to call BeginInvoke<br />
           BeginInvoke(new AddItemDelegate(AddItem), new object[] { text });<br />
	   return;<br />
       }<br />
       myListBox.Items.Add(text);<br />
   }<br />
<br />
   // Your DoWork event <br />
   private void myListBox_DoWork(object sender, DoWorkEventArgs e)<br />
   {<br />
       foreach( string item in myList )<br />
       {<br />
           AddItem(item);<br />
       }<br />
   }<br />
}<br />

static bool InstanceExists
        {
            get
            {
                bool notExists;
                mutex = new Mutex(false, "Local\\" + AppGuid, out notExists);
                return !notExists;
            }
        }
static Mutex mutex;
static string AppGuid = "";//put the AppGuid in here

if (!Program.InstanceExists)
{

}

interface IDrawableObject
{
     // implement as attributes
     ObjType type; // CIRCLE, RECT, LINE etc
     Vector4[] polygons; // x, y, z, color
     Vector3 translation;
     Vector3 rotation;

     public void Draw() { ... }
}

//in the first form
public static string textBoxText = "";

private void Button1_Click(object sender, EventArgs e)
{
  textBoxText = TextBox1.Text;
  Form2 f = new Form2();
  f.ShowDialog();
}

//in the second form
private void Form_Load(object sender, EventArgs e)
{
 Label2.Text = Form1.textBoxText;
}