Sets the maximum number of items the combo box can hold to <num>. If <num> is smaller than the current number of items, the list is truncated at the end. There is no limit by default.
Make the input field editable, if <bflag>. Otherwise the user may only choose one of the items in the combo box. If the parameter is ommited, it is assumed to be false.
This function is called by the framework when a new item has activated. The index value is the position of the new item. The default implementation emits the $activated() signal,
This function is called when the text in an editable combobox has changed. The function return the new text in its argument. The default implementation emits the $textChanged() signal.