Both Save As.. and Save a Copy... native dialogs on Win32 fail to suggest any default file name to save to.
Note this was with the Win32 Snapshot from June 18, 2008.
Very close to bug #171932 (Default filename in "Save as" dialog). Marked duplicate. Please comment if you think it's not the case. Thanks!
Bug watches keep track of this bug in other bug trackers.
Note this was with the Win32 Snapshot from June 18, 2008.