Public Class PictureBox : Inherits Windows.Forms.PictureBox
    Private m_tooltip As ToolTip
    Private m_bmp As Bitmap
    Private m_hotSpots As New HotSpotElementCollection

    Public Sub New()
        InitializeAsSmartPictureBox()
    End Sub

    Public Property MapImage() As Image
        Get
            Return DirectCast(m_bmp, Image)
        End Get
        Set(ByVal value As Image)
            m_bmp = New Bitmap(value)
        End Set
    End Property

    <DesignerSerializationVisibility(
     DesignerSerializationVisibility.Content)> _
    Public ReadOnly Property HotSpots() As HotSpotElementCollection
        Get
            Return m_hotSpots
        End Get
    End Property

    Private Sub InitializeAsSmartPictureBox()
        If Me.SizeMode = PictureBoxSizeMode.Normal Then
            m_tooltip = New ToolTip
            m_tooltipTitle = "You’re on"
            AddHandler Me.MouseClick, AddressOf OnClickInternal
        End If
    End Sub
    ...
End Class

Imports System.Collections.ObjectModel

Public Class HotSpotEventArgs : Inherits EventArgs
    Public HotSpot As HotSpotElement
    Public CancelTooltip As Boolean
End Class

Public Class HotSpotElement
    Private m_hotSpotColor As Color
    Private m_hotSpotID As Integer
    Private m_description As String
    Private m_title As String

    Public Property HotSpotColor() As Color
        Get
            Return m_hotSpotColor
        End Get
        Set(ByVal value As Color)
            m_hotSpotColor = value
        End Set
    End Property

    Public Property HotSpotID() As Integer
        Get
            Return m_hotSpotID
        End Get
        Set(ByVal value As Integer)
            m_hotSpotID = value
        End Set
    End Property

    Public Property Description() As String
        Get
            Return m_description
        End Get
        Set(ByVal value As String)
            m_description = value
        End Set
    End Property

    Public Property Title() As String
        Get
            Return m_title
        End Get
        Set(ByVal value As String)
            m_title = value
        End Set
    End Property

    Public Overrides Function ToString() As String
        Return String.Format("HotSpot: {0} ({1}-{2}-{3})", _
            HotSpotID, HotSpotColor.R, HotSpotColor.G, HotSpotColor.B)
    End Function
End Class

Public Class HotSpotElementCollection
        Inherits Collection(Of HotSpotElement)
    Public Function ContainsColor(ByVal clr As Color) As Boolean
        For i As Integer = 0 To Me.Count - 1
            Dim elem As HotSpotElement = Me.Item(i)
            If elem.HotSpotColor.ToArgb() = clr.ToArgb() Then Return True
        Next
        Return False
    End Function

    Public Function FindHotSpot(ByVal clr As Color) As HotSpotElement
        For i As Integer = 0 To Me.Count - 1
            Dim elem As HotSpotElement = Me.Item(i)
            If elem.HotSpotColor.ToArgb() = clr.ToArgb() Then Return elem
        Next
        Return Nothing
    End Function

    Protected Overrides Sub InsertItem( _
            ByVal index As Integer, ByVal item As HotSpotElement)
        If Not ContainsColor(item.HotSpotColor) Then
            MyBase.InsertItem(index, item)
        End If
    End Sub

    Protected Overrides Sub SetItem( _
            ByVal index As Integer, ByVal item As HotSpotElement)
        If Not ContainsColor(item.HotSpotColor) Then
            MyBase.SetItem(index, item)
        End If
    End Sub
End Class

Protected Overridable Sub OnClickInternal( _
            ByVal sender As Object, ByVal e As MouseEventArgs)
    PrepareAndRaiseClickEvent(e.X, e.Y)
End Sub

Private Sub PrepareAndRaiseClickEvent( _
        ByVal x As Integer, ByVal y As Integer)
    Dim elem As HotSpotElement = GetUnderlyingHotSpot(x, y)
    If elem Is Nothing Then
        HideTooltip()
        Return
    End If

    ‘ Raise an event to the host form with the underlying color
    Dim args As New HotSpotEventArgs
    args.HotSpot = elem
    RaiseEvent HotSpotClicked(Me, args)
End Sub

Private Function GetUnderlyingHotSpot( _
        ByVal x As Integer, ByVal y As Integer) As HotSpotElement
    If Not m_beSmart Then Return Nothing

    ‘ Ensure the point is inside the bitmap
    If x >= m_bmp.Width Or y >= m_bmp.Height Then Return Nothing

    ‘ Get the underlying color and check it against HotSpot collection
    Return HotSpots.FindHotSpot(m_bmp.GetPixel(x, y))
End Function

Private Sub HideTooltip()
    m_tooltip.SetToolTip(Me, String.Empty)
End Sub