I'm on OSX 10.8.5, and was hoping 4.0EA1 would resolve a long-standing issue I've had with the product around stale database connections.
I use SQL Developer at work, and almost always have a handful of connections open to various remote 11Gr2 databases. When my local machine goes to sleep or disconnects from WiFi temporarily, those connections still appear to be "active" in SQL Developer (connection icon has the little plug on it), but trying to use that connection shows that it is not operable (executing a query results in some sort of connection closed/timeout sort of message). This by itself is a UI glitch/bug that is annoying - either the connection is gone and the UI should reflect that and behave as if the connection is gone, or the UI should "revive" the connection when I try to use it.
However, I could deal with that issue. The more significant issue for me is that when I try to manually reconnect/disconnect/etc, SQL Developer hangs for 10-30 seconds before responding. To be specifc, I right-click the connection and nothing happens for this time period. Eventually, I am able to reconnect or disconnect, depending on what I am trying to do. But each connection I need to reconnect/close makes me go through this same painful process. Closing SQL Developer normally (using the menu, "Quit Oracle SQL Developer") also hangs.