I suggest to resize (at least) buttons automatically, if the content does not fit into the default size. This would prevent ugly defects with different translations like the one I was pointed recently.
The problem is, that in some short english/german words can not be translated into a short word in all other languages, e.g. "Preview" is ""Предварительный просмотр" in russian, which does not fit into button even abbreviated to ""Пред. просмотр". I think this situation happen with a couple of other languages too.
I am not familiar with MFC (I guess this is what you use), but e.g. Qt4 implements this behavior by default.
I've made a small mockup of a "Tag - Filename" dialog with 2 translations to show you what I mean (see attachments). You should be even able to compile and run it if you have >=Qt4.2 installed.
mp3tag_dialog_mockup.zip (4.01 KB)