Some suggestions

[xnolduser]

1 - A setting to adjust the sharpen level of "Browser -> Thumbnails -> Sharpen Thumbnails"

2 - High quality sharpen for "View -> Use sharpen". Today the sharpen implemented here add a lot of aliasing and pixelation to image even if used just 1% velue, is unusable. Here would be implemented the same sharpen available in "Effect...", that is very good.

3 - Filelist Toolbar customization

4 - Setting to use Shift + Mouse Buttons in "Interface -> Mouse" currently we can just use Ctrl for combinations.

5 - Open encrypted RAR 4-5 and ZIP archives, just show a popup to type the password. And add the context menu "Browse with XnviewMP" to this file types.

6 - A context menu entry to do an reverse image search using Google, Bing and TinyEye.

7 - Keyboard shortcuts to temporally set the Contrast, Bright and Saturation, and to Reset the values, like in Potplayer, you can use Q to Reset, W and E for more or less Bright, R and T for more or less Contrast, Y and U for more or less Saturation. This would be useful when in fullscreen, when you dont want really edit the image but just adjust for a quick and better view of a bad image.

Thanks a lot for the best image viewer available! Congrats!

[xnolduser]

If implemented reverse image search, need the options to use SHA1 and SHA256 hashs of the images as a parameter on URL, services like Tineye search for images using hashs, for example Tineye use SHA1. Tineye also accept search using img url but some img hosts block the access, so the only way to search in this cases is using hash.