Don't use double-click pattern in client

[eloquence]

The current client code requires a double-click to trigger download actions. We should avoid using a double-click pattern anywhere in the client. This is a heuristic observation, i.e., we cannot easily verify in user tests against the prototype whether users double-click, but it's consistent with common application behavior, especially considering that we have some web-style buttons and links in other parts of the application.