This method presents the user with the drop-down editor to assist in data entry. If the control is disabled or the DropDown.GrapeCtiy.Win.Editors.DropDown.AllowDrop property is false, a call to this method is ignored.
When the drop-down editor is just about to display, the DropDownOpening and DropDownOpened events are triggered.
This method will try to seize focus when the control does not have the input focus.