I would like auto-hide histogram and exif info panel. Maybe something similar as FastStone Image viewer. This freeware is more slowly and skin is terrible, but auto hide right panel + top panel with image thumbnail is excelent idea. With fastpictureviewer clean and transparency design it could be very nice.
And SIB suggestion with new button 'Folders' on menu bar with pre-selected folder is great
This is very usefull thing for many users