Please add transparency grid option for png in the project panel icon view.
As you can see in this image, the storyboard images on the right do not display correctly in the project panel icon view, because transperancy is rendered as black. Please add an option to render transperancy as a grid in the same way that you can do this in the source window.
I often use premiere pro to make moving storyboards for animations, adding this option would make my work easier.