BUG REPORT: Vivaldi does not observe OS X menu and menu bar conventions
Among the OS X conventions Vivaldi for Mac fails to observe: [ol] [li][b]About Vivaldi[/b] in the Vivaldi menu currently does nothing. It should instead do what Help>About currently does—display Vivaldi's About window or page. Help>About should not exist.[/li] [li]There is no [b]Preferences[/b] item in the Vivaldi menu. Instead, there is a [b]Settings[/b] item under the Tools menu. This should be moved to Vivaldi>Preferences. (cmd-, does currently launch the Preferences window, which is correct Mac behavior.)[/li] [/ol]
I think I reported the "Vivaldi > About Vivaldi" doing nothing bug via bug report form awhile back. I imagine it'll likely get fixed before long, since it should be trivial to rectify.
Also: With regards to flouting OS X conventions, right now the bookmarks menu is showing up as the leftmost menu (aside from the menu), to the left even of the Vivaldi menu, so that's also somewhat odd. (Edit: Whoops, that "Bookmarks" menu only appears if you open and then close/switch away from the element inspector/dev tools. Another thing to file…)
Update: In 184.108.40.206 (TP3):
✓ Vivaldi > About now works.
✓ Help > About has been removed.
✓Settings has been moved to the Vivaldi menu…
✗ However, the standard OS X convention would be to label it "Preferences… ⌘,".