private void Apply(object selectedMenuItem) { MemberModel selectedModel = selectedMenuItem as MemberModel; if (selectedModel == null) { return; } selectedModel.Age = ListPageMemberModel.Age; string error = ListPageMemberModel.EnableValidationAndGetError(); if (error != null) { return; } TreeCategory oldParent = selectedModel.Parent; TreeCategory newParent = TreeViewMaker.FindNewParent(TreeItemModel.TreeCategories, ListPageMemberModel.Age); if (oldParent.Equals(newParent)) { return; } oldParent.Children.Remove(selectedModel); newParent.Children.Add(selectedModel); newParent.IsExpanded = true; selectedModel.IsSelected = true; }