Implement test to delete child element and make it pass.

zaaReloaded2/ViewModels/SettingsViewModel.cs

@@ -135,6 +135,7 @@ namespace zaaReloaded2.ViewModels
                     vm = new ControlElementViewModel(element as ControlElementBase);
                     foreach (FormatElementViewModel childVM in ((ControlElementViewModel)vm).Elements)
                     {
+                        childVM.Parent = vm as ControlElementViewModel;
                         childVM.PropertyChanged += ElementViewModel_PropertyChanged;
                     }
                 }