The idea is to introduce a way for UI extensions to indicate if they can be executed asynchronously.
- serialize and restore a selective list of contextual datas
- caching: based on the task identifier and the cached context information, also allow the lifetime
- skinx support: a protocol to allow asynchronous tasks to transmit css/js links to load
- disabling async: an URL parameter and a context property to force disabling asynchronous stuff, need for html/pdf export for example