1.Click ComboBox in Toolbox, and then click and drag on the right pane to create a new ComboBox. 2.Add sub-groups to the new ComboBox. 3.Select the new ComboBox0.SelectedIndex and click SelectionChanged under Event to trigger and run a function (A, B, or C function). 4.Click different sub-groups under the new ComboBox to switch pages or functions.