134 lines of code, 4 normal functions, 20 calls to chrome.something APIs, some of them nested, 0 const, 0 let, 0 var, 0 ESLint errors, 0 Vivaldi debugger errors.
5h wasted with refactoring and debugging because I wanted to make it run, but it didn’t want to work as I wanted and I thought I am an idiot – until I cross checked in naked Chromium.
Result: I am not an idiot.
There are at least 4 BUGS in Vivaldi’s implementation of multiple browser windows, extensions buttons and history display handling.
This is no fun.