Dim MerkFeld As Feld
 
  Protected Overrides Sub OnMouseLeave(e As EventArgs)
    ÜberFeld = Nothing : MerkFeld = Nothing
    Me.Refresh()
  End Sub
 
  Protected Overrides Sub OnMouseMove(e As MouseEventArgs)
    If Gestartet AndAlso e.Button = MouseButtons.None Then
      ÜberFeld = FeldUnterMaus(e.Location)
      If ÜberFeld IsNot MerkFeld AndAlso AktFeld Is Nothing Then
        MerkFeld = ÜberFeld
        Me.Refresh()
      End If
    End If
  End Sub