I remember seeing the mouse gestures in Opera and wanting the same feature in my Firefox. I used this in Firefox with an extension for several years and later did the same with Chrome. Now with Vivaldi I accidentally performed a mouse gesture due to muscle memory and to my surprise it worked out of the box.

With the same people behind it this browser seems to be the real successor for Opera. :)

Try tab tiling: ctrl-select two (or more) tabs and select "Tile tabs" from their context menu.