Here is how it would do it.
VB Code:
  1. Private Sub tbbNavigation_Click(ByVal sender As Object, ByVal e As System.Windows.Forms.ToolBarButtonClickEventArgs) Handles tbbNavigation.ButtonClick
  2.     Select Case Me.tbbNavigation.Buttons.IndexOf(e.Button)
  3.         Case 1
  4.             'Back
  5.             Me.ContextMenu1.Show(Me.tbbNavigation, New Point(e.Button.Rectangle.Left, e.Button.Rectangle.Bottom))
  6.         Case 2
  7.             'Next
  8.         Case 3
  9.             'Home
  10.         Case 4
  11.             'Search
  12.     End Select
  13. End Sub