In the loop, where you are looping through each of the eight color buttons on the toolbar,
you use the SetButtonStyle function to control the behavior of the toolbar buttons. The
first argument to this function is the index of the button that you are changing. The second
argument is the style of button that you want for the toolbar button specified. In this
case, you are specifying that each of the buttons be TBBS_CHECKGROUP buttons, which
makes them behave like radio buttons, where only one of the buttons in the group can be
selected at any time. The list of the available button styles is in Table 12.3