BCGControlBar Pro for MFC
int CBCGPRibbonUndoButton::GetActionNumber ( ) const

Returns the number of actions selected by the user.

The button's command is executed when the user either clicks the button itself, or selects a number of commands from the drop-down list. You need to call this method in the first case in order to determine how many actions has been selected. In the second case the returned value will be -1.