Another few suggestions

[kajman]

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

[tossporn]

Thanks a lot for such a great viewer, especially on CMS.

I also experienced that histogram is created from the image after chromatic adaptation was done.
So, normally, software should build histogram base on original RGB value.

I also have another 2 suggestion, concern Histogram, which are..
1. The option for user to select opacity value of display panel of histogram and information.
2. The option for user to select whether histogram based on RGB or Lightness (luminance).

[Axel]

The opacity of all floating windows can now be user-selected from 20% to 100% in 20% increments. An "Opacity" sub-menu was added to each window's context menu, accessible by right-clicking within the withdows themselves.