Use a ContentTemplate and determine whether the control contains content
//File:Window.xaml.vb
Imports System
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Documents
Imports System.Windows.Navigation
Imports System.Windows.Shapes
Imports System.Windows.Data
Imports System.Windows.Media
Imports System.Collections.ObjectModel
Namespace ContentControlSimple
Public Partial Class Page1
Inherits Canvas
Private Sub OnClick(sender As Object, e As RoutedEventArgs)
If contCtrl.HasContent = True Then
MessageBox.Show("contCtrl has content")
End If
End Sub
End Class
End Namespace