TCustomCombo = class(TCustomListControl)
class PASCALIMPLEMENTATION TCustomCombo : public Vcl::Controls::TCustomListControl
TCustomCombo is the base class for all combo boxes.
Use TCustomCombo as a base class when defining a control that represents a specialized combo box. A combo box is an edit box with a scrollable list attached to it; users can select an item from the list or type directly into the edit box. Combo boxes can present the list as a drop-down list or as a list box that is always visible.
Typically, combo box classes do not descend directly from TCustomCombo. Rather, they descend from one of TCustomCombo's descendants, TCustomComboBox or TCustomComboBoxEx. Use TCustomCombo as a base class for a simple combo box, or TCustomComboBoxEx as a base class for a combo box that supports the extended combo box features such as images on the list entries.