1. It would be nice if the preview button on the toolbar remembered the last type of preview selected and showed it as the visible icon. Right now, if you are constantly using Debug Preview, you can only select it from the drop down menu. What I would like to see is the Debug icon as the visible icon on the toolbar if that was the last mode that I used.
2. Also, you would need to visibly differentiate between Preview Layout and Preview Project because right now they are the same. Here is my suggestion for this.