Allowing Toggled Tool Buttons
Go Up to Adding a Toolbar Using the Toolbar Component
Use AllowAllUp to create a grouped tool button that acts as a toggle: click it once, it is down; click it again, it pops up. To make a grouped tool button a toggle, set its AllowAllUp property to True.
As with speed buttons, setting AllowAllUp to True for any tool button in a group automatically sets the same property value for all buttons in the group.