Just submitted a bug fix for a critical bug in the ExternalScreen plugin: https://github.com/phonegap/phonegap-plugins/pull/366
There was an incorrect method of loading local HTML content in the UIWebView displayed in the external screen. This issue caused all linked content with a relative URL to fail. The PGExternalScreen.m file was updated to use [NSURL fileURLWithPath:path isDirectory:NO]; so that it can load linked content in the web via relative paths. Thanks! Andrew Trice
