Ability to use external download-manager
It would be nice if one could set up an external program to handle downloads. Maybe make at setting to set the command to run to add a download. I'm using uGet to download.. and it is quite taxing to have to copy/paste each link over every time I want to download.
On good download managers, like Jdownloader or the good old (but still unmatched on some aspects) Get Right, there isn't any need to copy and paste.
Just copying the link(s) is more than enough (even if they aren't proper clickable ones, like a list of URLs opened in notepad).
No need to have (potentially harmful) mods inside the browser, and consistent behavior across all the programs (not just browsers)
It would certainly be nice to have a reliable downloader. In particular, having started a download that download should continue until the file has been completely downloaded, even if the Internet connection is intermittent and even if the browser is closed and reopened. If the download stops prematurely then the user should be alerted. Currently Vivaldi will silently stop.
In the absence of a built-in downloader with these features it would be nice to be able to automatically spawn wget.