Can xml support be added ?

[Rimits]

This is a great extension! Thank you! Now I want to set slideshow wallpapers (defined in xml) for different workspaces. So I append a line filter.add_pattern("*.xml"); to prefs.js at line 162. That works as expected like a charm and now I have 4 different slideshows. But there is a small issue is that the xml preview is not quite right. Thus, can you pls add a function that can read the xml and use perhaps the first image as the preview ? Thanks again!