If you use the Form's paint event to perform the drawing then add Me.Invalidate()
into the properties' set method
Public Property ProRayonZoneElectrodeEnCases() As Integer
Get
Return rayonZoneElectrodeEnCases
End Get
Set(value As Integer)
rayonZoneElectrodeEnCases = value
Me.Invalidate()
End Set
End Property
This forces the form to refresh itself. See here: http://msdn.microsoft.com/en-us/library/system.windows.forms.control.invalidate%28v=vs.100%29.aspx