Esme Povirk (@madewokherd) commented about dlls/comdlg32/itemdlg.c:
{ WCHAR extbuf[MAX_PATH], *newext = NULL;
if(This->filterspec_count)
if(This->current_filter) {
newext = get_first_ext_from_spec(extbuf, This->filterspecs[This->filetypeindex].pszSpec);
newext = get_first_ext_from_spec(extbuf, This->current_filter);
Will it really add an extension from a manually-typed filter?