Today I spasmed while my mouse was over the side panel - and it disappeared! To be more precise, it appears to have shrunk to a column of exactly one pixel wide. I can toggle this on and off with the toggle button at the bottom. However, I cannot grab and widen it again. Can anyone suggest how I might fix this? Perhaps the "last width" is stored in a configuration file somewhere? I'm using the latest version. Instant update: I have just upgraded from 1.2.490.3 to 1.2.490.32 and now the issue remains except I cannot see the one pixel wide column. Toggling the panel on and off bounces the content of the web page around but appears to have no other effect...
It will doubtless be restored if you refresh your profile. Your profile folder is specified on the Help/about page. If you re-name the Default folder while the browser is closed, the browser will make a new folder when you open it again, and restore all of your settings to "factory," after which you can move your critical data from the old, re-named folder to the new one, and get your bookmarks, passwords, etc. back. From that point, it's best to select your settings from within the browser and install new extensions, if any, rather than moving these from the old profile. It takes eight or nine minutes but I can't think, offhand, of another way to restore that panel.
Just click the panel toggle again.
The panel toggle shows/hides the panel toolbar or whichever panel happens to be open.
Try changing the panel position from left to right in settings, and enable/disable the panel toggle.
Thanks for the replies, and sorry for the delay.
Toggling left/right etc. had no effect - the panel moved about but remained blank!
Ayespy's suggestion was the only solution. I renamed the Default folder to Default_old, then opened then closed Vivaldi again to create a new Default. At first, I tried to be really lazy and copied everything over, but this copied the broken panel. So, I closed again, deleted Default, reopened and closed Vivaldi and tried a more selective group of files. I chose only the relevant sounding files in the root of the profile, plus the three folders "Session Storage", "Sessions" (I had previously saved my "final" session) and "Local App Settings" (for the saved searches). However, this also caused the broken panel. After a process of elimination, I narrowed it down to the file "Current Session". I could copy everything else over, and as long as I left that file out, the panel remained unbroken. I could then restore my last session from the saved sessions without issue, and re-install my few extensions afresh.
I then had an idea: renaming the new Default to "Default_new" and setting "Default_old" back to "Default", I tried simply deleting the "Current Session" file. Sadly, this did not fix the problem, so the "broken code" must also reside somewhere else. However, I hope this gives a clue to someone else.