I think we we will have to handle protocols to do stuff as:

• A CSS loaded with plugin:X://resources/css/a.css will have all its relative resources prefixed by /CONTEXTPATH/plugins/X/resources/css
• idem with skin:
• idem with template:
• idem with workspace ? (we can, but the resources/ folder is not mandatory there

But if the protocol is another one, or if it leads to a non resources directory, we do not know to which url convert it, and should crash