public void NewButtonClicked(object parameter)
        {
            TabControlExt     tabControl = parameter as TabControlExt;
            int               count      = tabControl.Items.Count + 1;
            TabItem_ViewModel new_model1 = new TabItem_ViewModel()
            {
                Header  = "tabItem" + count,
                Content = "This is the content of " + count + " tabitem."
            };

            tabItems.Add(new_model1);
        }
        public void PopulateCollection()
        {
            TabItem_ViewModel model1 = new TabItem_ViewModel()
            {
                Header  = "tabItem1",
                Content = "This is the content of 1 tabitem."
            };
            TabItem_ViewModel model2 = new TabItem_ViewModel()
            {
                Header  = "tabItem2",
                Content = "This is the content of 2 tabitem."
            };

            //Adding tab item details to the collection
            tabItems.Add(model1);
            tabItems.Add(model2);
        }