The toolbar sample shows the wxToolBar class in action.
The following things are demonstrated:
Some buttons in the main toolbar are check buttons, i.e. they stay checked when pressed. On the platforms which support it, the sample also adds a combobox to the toolbar showing how you can use arbitrary controls and not only buttons in it.
If you toggle another toolbar in the sample (using Ctrl-A) you will also see the radio toolbar buttons in action: the first three buttons form a radio group, i.e. checking any of them automatically unchecks the previously checked one.