The following combo-box styles are available in MFC.
CBS_AUTOHSCROLL Automatically scrolls the text in the edit control to the right when the user types a character at the end of the line. If this style is not set, only text that fits within the rectangular boundary is allowed.
CBS_DISABLENOSCROLL The list box shows a disabled vertical scroll bar when the list box does not contain enough items to scroll. Without this style, the scroll bar is hidden when the list box does not contain enough items.
CBS_DROPDOWN Similar to CBS_SIMPLE, except that the list box is not displayed unless the user selects an icon next to the edit control.
CBS_DROPDOWNLIST Similar to CBS_DROPDOWN, except that the edit control is replaced by a static-text item that displays the current selection in the list box.
CBS_HASSTRINGS An owner-draw combo box contains items consisting of strings. The combo box maintains the memory and pointers for the strings so the application can use the GetText member function to retrieve the text for a particular item.
CBS_LOWERCASE Converts to lowercase all text in both the selection field and the list.
CBS_NOINTEGRALHEIGHT Specifies that the size of the combo box is exactly the size specified by the application when it created the combo box. Normally, Windows sizes a combo box so that the combo box does not display partial items.
CBS_OEMCONVERT Text entered in the combo-box edit control is converted from the ANSI character set to the OEM character set and then back to ANSI. This ensures proper character conversion when the application calls the AnsiToOem Windows function to convert an ANSI string in the combo box to OEM characters. This style is most useful for combo boxes that contain filenames and applies only to combo boxes created with the CBS_SIMPLE or CBS_DROPDOWN styles.
CBS_OWNERDRAWFIXED The owner of the list box is responsible for drawing its contents; the items in the list box are all the same height.
CBS_OWNERDRAWVARIABLE The owner of the list box is responsible for drawing its contents; the items in the list box are variable in height.
CBS_SIMPLE The list box is displayed at all times. The current selection in the list box is displayed in the edit control.
CBS_SORT Automatically sorts strings entered into the list box.
CBS_UPPERCASE Converts to uppercase all text in both the selection field and the list.