It would be nice if QCompleter could search substrings while creating a world list to propose for completion. If there is a text 'AABBCCDDEEABC' and we type AAB, QCompleter will suggest this word for completion, but if we type 'DDEE' it will not. It would be terrific if QCompleter had an option (could be a flag) to enable advanced completion by searching in substrings. (the same way Firefox 3.x.x does when you want to type a part of URL, you don't need to now what are the first letters of the URL because you can type from the middle). The next improvement could be a completion assuming that the typed text is a regular expression (using flag for QCompleter completion type might be a good idea) .