C#

public static void shuffle(int[] array, Random rand)
{
    for (int i = array.Length; i > 1; i--)
    {
        int j = rand.Next(i);  // use this instead of modulo!
        int tmp = array[j];
        array[j] = array[i - 1];
        array[i - 1] = tmp;
    }
}

this.tree.DrawMode = TreeViewDrawMode.OwnerDrawText;
this.tree.DrawNode += new DrawTreeNodeEventHandler(tree_DrawNode);

void tree_DrawNode(object sender, DrawTreeNodeEventArgs e)
{
    if (e.Node.Level == 1)
        HideCheckBox(e.Node);
    e.DrawDefault = true;
}

private void HideCheckBox(TreeNode node)
{
    TVITEM tvi = new TVITEM();
    tvi.hItem = node.Handle;
    tvi.mask = TVIF_STATE;
    tvi.stateMask = TVIS_STATEIMAGEMASK;
    tvi.state = 0;
    IntPtr lparam = Marshal.AllocHGlobal(Marshal.SizeOf(tvi));
    Marshal.StructureToPtr(tvi, lparam, false);
    SendMessage(this.tree.Handle, TVM_SETITEM, IntPtr.Zero, lparam);
}

Form f1;

//Code for ChildForm which is
derived from ParentForm.
Public ChildForm():base(this)
{
}

//And here is constructor of ParentForm
//from which ChildForm is derived.
public ParentForm(Form _f1)
{
    f1=_f1;
}