Right-click the toolbar control, Properties-> Button-> Select the button you want to make a button menu-> If the style attribute is set to 5tbdropdown, click "Apply", and you will see a small drop-down arrow on the right side of the selected button in the interface, and then edit the button menu you want in the button menu column below.

Application:

The menu responds to the ButtonMenuClick event, and the menu can distinguish which menu submitted the event by the index or key returned by the event.