I had complained about this sometime ago and most of it got fixed and the site in general is a lot better.
But there is one thing annoying about that "Insert with the Quote editor button" popup :
1. Select some text
2. even while the popup is being shown select some other text
3. Do 2 many times
When you're done with doing this, I'd expect the popup to be shown one last time for the last text I selected.
But what happens is that it gets shown a lot many times. The problem can be replicated even easily with double-clicking on text.
Though I'm not really knowledgeable here, I think this should be an easy fix.