Got new plugin idea (idea is based on this plugin), not sure if you will be interested or got time to implement, or if it’s even possible.
Anyway: Will it be possible to parse css and find out classnames [and maybe ids], then if you cursor is in following position
Also noticed that currently your plugin shows autocompletion list even if cursor is inside classname or id. I see that sublime doesn’t tell you what kind of attribute you are editing, but maybe it is possible to read current string where cursor is and find out if you are editing ‘src’ or ‘href’ (I think only these two recuire filenames autocompletion).
Again, thank you very much for this plugin, really nice work!