I asked on IMDB and I found it!
It's call THE LITTLE FOX (1981)
It appears to be out of print, but maybe I'll try and find a copy on ebay. Has anyone here ever heard of this movie? It doesn't seem to be too well known.
The IMDb boards are great. There is a lot of knowledge there.
A Hungarian film, eh? Did you see it in the US, or over in Germany (or another country)? I was wondering if this had been dubbed and released over here. Finding a copy could be a difficult search, though animated films tend to be a little easier for some reason - perhaps demand. Still, it is quite likely you will be dealing with a gray market seller when you find a copy; so, as always online - buyer beware.