Currently, AIR's HTML control doesn't handle pointing to an image or file. That means if you click a button / link which points to a file / image. The HTML control will show blank white.
If you want to work around this, get all hyperlinks in the html page, make it call your function onClick.
Otherwise, implement a custom HTMLHost, and whenever you detect a change to a location, if it is a file or image / use URLLoader to download the file / image instead of redirecting the HTML control.
I have been able to get the HTML control to render PNG files by setting the url, ie http://mapalist.com/images/icons/googleblue.png
However, I am unable to (at the present time) to detect or handle file downloads...
If anyone has an insight, I am all ears.
Will update if I come across anything.
This Adobe Flex Bug seems to encapsulate what we might be looking for:
I had the same problem and used the following:
I wanted to allow downloads from my own application so I adapted the second of these to only work on links I tag sepecially with an id. If you want this method let me know.
From what I have found out, there seems to be no real way of reproducing the standard browser download behaviour in AIR yet, although I may be wrong.