In the web client, the user would like to be able to multi-select the resources. Current behavior in 14sp3 is a select one resource click Add, then select resource two and click Add.

It would be nice it they could click 5 in the same set of resources and then Add once.

2nd usable request is related to what happens when you click Add. Currently if you have no resources you see the GUID is populated and it gives a great visual to confirm the Add function completed a task since the window does not close until you click close.
The 2nd issue is when you already have 10 or more resources and click Add there is no visual to show you the file is added. Could we scroll to the bottom of the resource list to show the new one? Or present some other hint that something happened?