void complete(string pattern
Use this method to match a particular string to valid file names and
sub-directories in the current directory. If a match is made, the
matched file/directory name will appear in the text entry field of the
file selection prompt. If partial matches have been made, the files are all
listed in the files list (usually on the right hand side) and the
sub-directories in the directories (usually on the left hand side) list.