VB Drop Down Toolbar Help!

Hello,

I'm developing an application that uses a Toolbar. My toolbar has a Drop Down on it.

Is there a way when you click the Parent button of the Drop Down it will automatically display the drop down contents?
(Not by clicking the Drop Down of the parent button). I really wanted to use the parent button of the drop down to display the drop down contents.

Maybe APIs can help to my problem but I don't know what API should I use.