BCGControlBar Pro for MFC
void CBCGPRibbonEdit::SetAutoCompleteList ( BOOL  bSet = TRUE,
COLORREF  clrHighlightedText = CLR_NONE,
COLORREF  clrHighlightedFill = CLR_NONE 

Specifies whether the auto-complete mode is enabled.

bSetIf this parameter is TRUE, this control has an auto-complete mode.
clrHighlightedTextHighlighted part foreground color.
clrHighlightedFillHighlighted part background color.

Call this method to enable/disable control's auto-complete mode. When auto-complete is specified, the list of the matched suggestions will appear under the edit box when user types the text. To fill the list with matched items, you have to handle a registered message BCGM_RIBBONEDIT_ON_FILL_AUTOCOMPLETE_LIST in the Ribbon owner window class (usually CMainFrame).