The 2015 Image Viewer for Windows x64 is an MSI installer ending up in \Program Files\xeraina\ImageViewer, apparently it ignores (= does not touch or uninstall) an older \Prigram Files (x86)\xeraina\ImageViewer. The MSI installer somehow failed to associate PGF files with their viewer, I used regedit to fix that:
Rename open to view for the Windows photo viewer, add open for ImageViewer, keep printto as it was, and do not touch the view/droptarget, presumably I should move or copy that to open/droptarget. So far for the installation blues, complete with two reboots and two repair installations until I figured out that having two PGF ImageViewers is better than only the Windows Photo viewer.
The old ImageViewer claims to use a 32bits 6.13.12 codec, I guess that this is the PGFwic.dll in \Prigram Files (x86)\xeraina\ImageViewer. The bew ImageViewer claims to use a 32bits 7.15.32 codec. Is 32bits as it should be? I'm willing to use regsrv32 and/or regedit if necessary.
Disclaimer, I only use PGF for comparisons with WebP, BPG, JLS, JXR, J2K, and sometimes I update pages like WIC
