Not working properly with Blogger engine
Using the Blogger platform, Vivaldi is not forming the entire editing toolbar when creating or editing pages. What's more, Vivaldi does not complete the processing of uploaded images, so it impossible to add them to a page.
I tested the process in Slimjet, and it went through with no problem. The toolbar was fully present as well.
I'm on vivaldi 1.6.689.46 on Linux.