By default, the AutoDropDown property is False. The property has effect only if the control's Style is DropDown or DropDownList.  

• If the Style property is DropDownList and AutoDropDown property is True, the control shows the drop down portion of the control when user clicks the control's label area, if the control's list is not empty. Use the Add method to add new columns. Use the AddItem or InsertItem method to add new items to the control's list. 

• If the Style property is DropDown and the AutoDropDown property is True, the control shows the drop down portion as soon as the user starts type characters. 

• If the Style property is Simple, the AutoDropDown property has no effect.

If the AutoDropDown property is False, the user can open the control's list be pressing F4 or by clicking the right drop down button. Use the DropDown method to show programmatically the drop down portion of the control.

If the AutoDropDown property is True, the user can automatically drop down portion of the control if any of the following key is pressed:

• digit keys from 0 to 9
• alpha keys from A to Z
• any of : ;:+,-.?~[{\|]}'"
• numeric keypad keys.