That is fine .. disagreement is good but you shouldn't have to DClick twice

I disagree. Selecting a node is to show it's contents, if you want to expand it, using the + or double click is fine.

It appears that I have to DClick twice to get the nodes to expand. For example I click on MediaMonkey Library. Nothing. Then Dclick it again and it displays the categories that I have set for serving. I Dclick on TV and there is a flash of 'Reading files...' at the bottom but nothing else happens. I have to DClick again to get it to expand to All Files,Location,Actor etc. Then Dclick on Series and again 'Reading files...' show but nothing else happens. DClick again and the series show.

You should be able to just click on an item and get the next level of things.

I don't know how much time you will want to spend time on this as it works much better with MM5 (though MM5 doesn't play files:) )