[REG 5.6.1-1 -> 5.6.2] quicknanobrowser shows red square instead of "zoom" icon on images

1. Run the quicknanobrowser example.
2. Open https://en.wikipedia.org/wiki/Qt_(software)#/media/File:Qt_logo_2015.svg
3. Move the mouse cursor over the image.
   It will be a red square instead of a proper "zoom" icon.

When zooming is possbile, the mouse pointer should look like a magnifying glass.