Setup X-Forwarded-Proto in GUI?

[randybarth]

How would I implement the following configuration in the HAproxy GUI?
[...]
frontend web-https
option http-server-close
http-request set-header X-Forwarded-Proto https if { ssl_fc }
[...]

Having an issue with PHP backend (Wordpress) displaying properly with SSL offload at front end and http to backend. It seems that I need to let PHP know that original request was TLS from client.