where to find "mask as"
I think I did simply over see it. Where is to find the "mask as (Firefox|Chrome|...)" feature?
Thanks in advance
As far as I know - Vivaldi doesn't have this option at the moment. So your only way seems to do this is via an extension:
https://chrome.google.com/webstore/search/user agent switcher?hl=en-US
@toohoo: Vivaldi doesn't officially have the feature, yet. You have to install a user-agent switcher extension, or run a command-line switch.
@zaibon thank you,
just what I was searching. I choosed the 3. But there seems to be no help. The URL-switcher is not intuitive. Did not get it right untill now. Have the difficultie to set mask for all frames or not for all.
@toohoo I normally don't use such extensions so I am not sure if I understood you correct but doesn't "Apply only to current Tab" solve your problem?