There are a number of C99'isms in xfce4-mixer's code (in particular declarations after executable statements), resulting in it not being able to compile in pre-C99 compilers.
Created attachment 64 Proposed patch This makes the code compilable, though some cleanup might be desirable
yeah, oops... should be fixed now
a note for future reference: if you're going to post a patch, don't compress it. if it's so large that it requires compression, don't mark it as a patch. this causes the webserver to send it (compressed) as text/plain, which it isn't.