Adds a string to a list box.
If the list box was not created with the LBS_SORT style, the string is added to the end of the list. Otherwise, the string is inserted into the list, and the list is sorted. If the list box was created with the LBS_SORT style but not the LBS_HASSTRINGS style, the framework sorts the list by one or more calls to the CompareItem member function.
Use InsertString to insert a string into a specific location within the list box.