import panel as pn
pn.extension()

menu_items = [('Option A', 'a'), ('Option B', 'b'), ('Option C', 'c'), None, ('Help', 'help')]

menu_button = pn.widgets.MenuButton(name='Dropdown', items=menu_items, button_type='primary')

pn.Column(menu_button, height=200)

menu_button.clicked

text = pn.widgets.TextInput(value='Ready')

def b(event):
    text.value = f'Clicked menu item: "{event.new}"'
    
menu_button.on_click(b)

pn.Row(menu_button, text, height=300)

pn.Column(*(pn.widgets.MenuButton(name=p, button_type=p, items=menu_items) for p in pn.widgets.MenuButton.param.button_type.objects))

pn.Row(pn.widgets.MenuButton(name='Split Menu', split=True, items=menu_items), height=200)

pn.Row(menu_button.controls, menu_button)