Shutdown port when all backends are offline

[info]

Hi,

I'm currently dabbling with additional round-robin DNS load balancing as 
addition to the normal HTTP lb with HAProxy. Now the problem seems to 
be, when one of the servers has a backend that is completely down, it 
will show an error page. Best case would be, the client shows only the 
error page, worst case is, the client loads half a web page from the 
frontend that is online and then breaks, because it loads scripts, 
styles or images from the frontend that is offline.

Now, when I just shut down HAProxy when all backends are down, 
everything will work just fine(except maybe for a slight delay on the 
first page load), because the second DNS entry is used and the server 
that is down is ignored.

Is there any way to control the frontend in that kind of way, that it 
does not listen on the assigned interface/port, when all backends are 
down?

Greetings,
mkzero