it seems that when we click "browse content" in user sandbox to see all contents generated with a Web Form, we seen only contents submitted to staging sandbox and not content waiting in user sandbox.
Is it normal ? Is there a way to see user contents + staging contents ?
This is the expected behaviour, although obviously it's not ideal from a usability perspective. The underlying issue here is that Lucene doesn't support virtualised (sandboxed) indexing, and the "browse content" lists are built via Lucene queries.