ComponentOne True DBGrid for WinForms
Detecting Built-In Combo Box Selections
Cell Editing Techniques > Drop-Down Controls > Detecting Built-In Combo Box Selections

The ComboSelect event is fired when the user selects an item from the built-in combo box. This event is useful for determining the contents of the cell before the user exits edit mode.

Since the items displayed in the built-in combo box are often the only allowable values for the underlying data source, you may need to prevent your users from typing in the cell after making a selection. By setting the C1DisplayColumn property DropDownList equal to True, the attached C1TrueDBDropDown control will now be limited to use only as a list box. No new values or changes will be allowed in the drop-down and so the underlying database cannot be updated with false information.