Keyboard shortcuts affect all windows on the same desktop at the same time
Here's a regression in 1.13 I've observed on Linux; I couldn't reproduce this one on Windows.
When I have multiple windows of Vivaldi open, keyboard shortcuts seem to take effect in all of them at the same time. For example, ctrl+t opens a new tab in each window. ctrl+shift+i toggles the developer tools in the active tab of each window (and also switches focus to another window; I assume it's to the last one in which the shortcut event gets processed). ctrl+w closes the current tab in all windows.
If it makes any difference, I'm running Gentoo, and I'm using qtile as the window manager. It looks like this affects all windows on the current desktop, but if one window is currently on a different desktop, it's not affected.
I can try to make a short screen recording when I get home, but it might take me a while.
I'm also using Gentoo, but with Fluxbox window manager. I've several Vivaldi windows on same virtual desktop - and don't have this issue on www-client/vivaldi-1.13.1008.32_p1.