Isn't this because showConnectionDialog() can potentially run asynchronously on a different thread?  Maybe we need a
showConnectionDialogFromEventThread() method?

    public void showConnectionDialog() {
        try {
            final ConnectionNodeInfo cni = findConnectionNodeInfo(getName());
            if (cni != null && cni.getConnection() == null) {
                Mutex.EVENT.readAccess(new Runnable() {
                    public void run() {
                        new ConnectAction.ConnectionDialogDisplayer().showDialog(cni, false);
                    }
                });
            }
        } catch (DatabaseException e) {
            Exceptions.printStackTrace(e);
        }
    }

It is possible. In my case the behavior was caused by a bug in my code (outside the DB Explorer). So I can't really
reproduce the issue, so closing.

The issue still exists in the latest netbeans. 
Product Version: NetBeans IDE 6.1 (Build 200805300101)

Invoking the same code second time around creates a connection successfully.
Here's the code that I use.

        final Object item = this.datasourceComboBox.getSelectedItem();
        if (item instanceof ConnectionWrapper) {
            final ConnectionWrapper cw = (ConnectionWrapper) item;
            this.selectedConnection = cw.getDatabaseConnection();
            
            ConnectionManager.getDefault().showConnectionDialog(this.selectedConnection);
            Connection jDBCConnection = this.selectedConnection.getJDBCConnection();
        }

In which thread are you calling getJDBCConnection()?

I have a JPanel which displays a comboBox with the list of connectionWrappers.
When the user selects one of the items, the actionPerformed(Event) calls the following method.

        final Object item = this.datasourceComboBox.getSelectedItem();
        if (item instanceof ConnectionWrapper) {
            final ConnectionWrapper cw = (ConnectionWrapper) item;
            this.selectedConnection = cw.getDatabaseConnection();
            
            ConnectionManager.getDefault().showConnectionDialog(this.selectedConnection);
            Connection jDBCConnection = this.selectedConnection.getJDBCConnection();
        }

Currently, the user has to select the comboBox item twice to get connected.

So it is the event dispatching thread, that is good. So there may be a race condition somewhere. But before I go hunting
it, could you please try to reproduce the issue against the newest build of 6.5? I recall fixing a race condition in the
code called by getJDBCConnection() some time ago. Thanks.

Have not heard from pponnala since August, assuming this is fixed.

v