Minor Issue & Suggestion
The current hover area for grouped tabs are troublesome when docked. Love the tab groups, however I'm not sure how much testing has been done with it when your browser is docked on the left or right side. Works perfectly when the browser is maximized, but when docked, the cursor turns into a resize cursor far too easily when trying to hover over the tiny rectangle. The day of mainstream ultra wide screens are very close. Would be nice if the hover area could extend below the inner grouping's tab, maybe even extend slightly into the top of the tab icon? When hitting the back/forward button, Vivaldi only accepts one request, and we're forced to wait for the page to reload before going back/forward again. But I know I want to go back 3 pages, and I don't want to move the cursor up to the back button and press it for 2 seconds to select the 3rd option! The panel concept is great, however re-sizing the panel is far too laggy. We're all looking forward to improvements there. Hotmail/Outlook doesn't let me log in using Vivaldi. Redirects to an error page. Works in Chrome/IE/Edge. Thanks for the great new browser.
The first issue has already been reported: see this thread.