The free text window boxes for regex and replace are scalable in size when stretching out the main window, but the "add prefix" and "insert" text boxes are fixed width. I frequently use the add prefix and insert functions when renaming mp3's, and it's a bit annoying to have to work in such a small box. Perhaps regex could be shortened to make some extra space for the add boxes? I suspect more people make use of the add functions than long reg expressions.