The screen shot “install_dnsgateway2.png” in installation handbook is superceded. I wanted to upload a replacement but can’t get the upload dialog to find files on my computer.
For info of other testers, it was prepared in KDE via “spectacle” screen-shot, directly exported to GIMP, cut, unsharp masked, then exported as PNG. My various PNG tools open it fine.
It tried Falkon, FireFox and Chromium browsers for the upload, all gave no apparent response to the “Browse” button but did upload something.
Thanks to those who tested this. It was my bad. I’ve been using openSUSE Leap 15.2 beta for some weeks and tend to forget that - and recently via core 143 testing branch.
Following Leap’s fairly frequent update, of 240+ files last night, the problem is not reproducible. All PNG, whether from “screenshot”, GIMP or LibreOffice, now upload, display their thumbnail and display within the wiki page. The only one of those apps that was replaced was LibreOffice.