The dropdown list of the Style Classes and Icons are pretty slow and more people are experiencing it. I think this is because of the fact that the whole list is loaded at once.
Second of all is that when you have selected a Style Class or Icon and it turns out that it is not suiting you, you want to select a better one. But the list won't start on your selected option, but on the top of the list. Again this is pretty annoying when the list is loading pretty slow and you have to scroll down again.