// Declare the drop-down button and the items it will contain.
internal ToolStripDropDownButton dropDownButton1;
internal ToolStripDropDown dropDown;
internal ToolStripButton buttonRed;
internal ToolStripButton buttonBlue;
internal ToolStripButton buttonYellow;

private void InitializeDropDownButton()
{
    dropDownButton1 = new ToolStripDropDownButton();
    dropDown = new ToolStripDropDown();
    dropDownButton1.Text = "A";

    // Set the drop-down on the ToolStripDropDownButton.
    dropDownButton1.DropDown = dropDown;

    // Set the drop-down direction.
    dropDownButton1.DropDownDirection = ToolStripDropDownDirection.Left;

    // Do not show a drop-down arrow.
    dropDownButton1.ShowDropDownArrow = false;

    // Declare three buttons, set their foreground color and text, 
    // and add the buttons to the drop-down.
    buttonRed = new ToolStripButton();
    buttonRed.ForeColor = Color.Red;
    buttonRed.Text = "A";

    buttonBlue = new ToolStripButton();
    buttonBlue.ForeColor = Color.Blue;
    buttonBlue.Text = "A";

    buttonYellow = new ToolStripButton();
    buttonYellow.ForeColor = Color.Yellow;
    buttonYellow.Text = "A";
    
    buttonBlue.Click += new EventHandler(colorButtonsClick);
    buttonRed.Click += new EventHandler(colorButtonsClick);
    buttonYellow.Click += new EventHandler(colorButtonsClick);

    dropDown.Items.AddRange(new ToolStripItem[] 
        { buttonRed, buttonBlue, buttonYellow });
    toolStrip1.Items.Add(dropDownButton1);
}

// Handle the buttons' click event by setting the foreground color of the
// form to the foreground color of the button that is clicked.
private void colorButtonsClick(object sender, EventArgs e)
{
    ToolStripButton senderButton = (ToolStripButton)sender;
    this.ForeColor = senderButton.ForeColor;
}