I don’t see this note in the upload instruction anymore. In the past there was a note about PHP scripts not being allowed in the preview files, and if you wanted to use a php script you would have to host it on your own server and use a crossdomain.xml file.
I wish to use this function. But what is the best way to setup the crossdomain.xml file? And if I want my preview to communicate with my server, what active den domain names should I insert into the crossdomain.xml file?