Public Class SideButtonBase 
   Inherits System.ComponentModel.Component

' Returns a SideButton instance for gcComboFrame1.
Private Function CreateSideButton() As SideButtonBase
    Dim sideButton As New SideButton()

    ' Specify a unique name for this button.
    sideButton.Name = "SideButton"

    ' Set button text.
    sideButton.Text = "Add a item"

    ' Set button's width.
    sideButton.ButtonWidth = 70

    ' Set this side button not to show in GcComboFrame.
    sideButton.Visible = ButtonVisibility.NotShown

    ' Set this side button to position at outside of GcComboFrame's right border.
    sideButton.Position = ButtonPosition.RightOutside

    ' Set the fat appearance for this button, and these settings will take effect when 
    ' its associated GcComboFrame's FlatStyle is Flat.
    sideButton.FlatAppearance.BorderColor = Color.Red
    sideButton.FlatAppearance.BorderSize = 2
    sideButton.FlatAppearance.CheckedBackColor = Color.Blue
    sideButton.FlatAppearance.MouseDownBackColor = Color.Yellow
    sideButton.FlatAppearance.MouseOverBackColor = Color.Green

    AddHandler sideButton.Click, AddressOf SideButton_Click

    Return sideButton
End Function

' Add a item into listBox1 when SideButton is clicked.
Private Sub SideButton_Click(ByVal sender As Object, ByVal e As EventArgs)
    If Me.textBox1.Text <> String.Empty Then
        Me.listBox1.Items.Add(Me.textBox1.Text)
        Me.textBox1.Clear()
    Else
        MessageBox.Show("You must input a string first !")
    End If
End Sub