So, wise masters, you say that instead of needing big hole in browser security, I just redefine problem.

Real problem is that single file upload is - select file - wait 1 minute for thumbnail compression - select next file - sit 30 minutes getting bored.

Best solution is have one page for multiple select, then go away have a Starkbier* and then all is done in background.

*=approved form of sustainance for monks