FYI re: Apparent Locking up with Google notifications from Google Calendar
Just an FYI for those that use G-mail and Google Calendar like I do.
I use Vivaldi on Linux, and don't know if this would affect other platforms.
A couple of times I thought Vivaldi had locked up on me. I would go to click a link on a webpage, and nothing would happen. It seemed as if it had frozen. I thought I would have to re-start Vivaldi.
Turns out the cause is: Google Calendar had notified me of a coming appointment, and I missed it (away from computer) and did not OK it it by going to the Calendar tab & clicking the OK on the Google Calendar page. Once I learned to check Google Calendar, all I had to do was click OK to the notification and all would go back to normal, and links worked in web pages in other tabs.
While I am sure it is a feature, this behaves like a bug, it took me a while to figure out this behavior as well.
That said, it makes me now check my Calendar if this happens, making it less likely for me to forget a calendar event. I'd rather have a little flashing icon alongside the extension icons than this happening, but once I figured it out - no problem.
I just figured out this is fixed with the 1.9 release.