How to fixed height of comboBox when one or more items are in list?

I create a dynamic ComboBox. and set height as

ComboBox cc = new ComboBox();

cc.DropDownHeight = 80;

In this comboBox when list of items are 10+ then its look like what I want.

But, in this comboBox list of items are one or two the comboBox height is small than 80.

Can you please solve this?