, если вы имеете в виду цикл в TabItem из TabControl:
public MainWindow()
{
InitializeComponent();
DispatcherTimer timer = new DispatcherTimer(DispatcherPriority.Background, Dispatcher);
timer.Interval = TimeSpan.FromSeconds(1);
timer.Tick += new EventHandler(timer_Tick);
timer.Start();
}
private int _selectedItem = 0;
void timer_Tick(object sender, EventArgs e)
{
tabControl.SelectedItem = tabControl.Items[_selectedItem];
_selectedItem = (_selectedItem + 1) % tabControl.Items.Count;
}