Usually, the title is just a string. However, if you have a multi column list with a custom display hook and you want to have seperate titles for each of your columns, you can set this attribute to TRUE. In this case, whenever MUI feels that the list title has to be drawn, it will call your display hook with a NULL entry pointer. Your hook has to check for this NULL entry and fill the given string array with your column titles. Layout of the column titles follows the same rules as layout of the lists entries.