Reporting several bugs
I'm a new Vivaldi fan, Unfortunately there are some bugs i have to report, below a copy and paste from my article reviewing this beautiful Browser: If you love to play flash-based online games like Darkorbit than i have to disappoint you. I get a grey screen with the message my flash player is out of date, which is not true. A disadvantage in my workflow is i am unable to drag an image into Photoshop. I need to copy a large image into my memory or save it temporary on my computer which is more time-consuming. It has also an issue with WordPress, when previewing an article it open an overview(backend) of all articles in a new tab instead of previewing the article. Thanks in advance!
As for DarkOrbit specifically, I don't play but my first thought is that you don't say which "flavour" Flash you have.
Because of the Chromium engine Vivaldi uses Flash PPAPI and NOT NPAPI.
Because of the "Out of date" message I suspect you have NPAPI installed.
If so, please go to get.adobe.com/flashplayer/otherversions/ and Select your Windows OS and then "Flash Player FP21 PPAPI for Chromium
As for dragging elements out of a tab/window, you are correct that this is not available (yet).
But it has been requested before and will come in a future version/release.
Note: you could post a link to your article in https://vivaldi.net/en-US/forum/vivaldi-on-the-web