Added my vote. I'm surprised this has so little attention.
Beyond Vivaldi's built-in screenshot feature, I'd also like to see support for external screenshot tools to do the exact same thing (take a pixel-perfect screenshot of the visible page, not the toolbars or panels), so that I can use my typical workflow for taking screenshots to also capture ideal screenshots in Vivaldi. The terminology I've seen around this is "control regions".
I use ShareX, a very popular screenshot tool. When using the "region capture" mode, hovering over a window will automatically size the region to the size of the window, which is a fantastic low-friction way to get a pixel-perfect screenshot every time.
Also, when having "Also detect control regions inside windows" selected (ShareX Region Capture setting), apps like Windows Explorer, Google Chrome, Notion, etc., automatically snap to various regions within the app: toolbar, side pane, main pane/web page, etc.
I would like Vivaldi to behave like this, giving us 2 or 3 panes that can be hovered over to provide different selection areas for ShareX. I think this same behavior should exist for the Vivaldi built-in screenshot tool, as others have mentioned above, and I'm wondering if identifying these "control regions" will be the appropriate development area to target to solve both at once.
I found another post about this, but it is archived so I cannot comment or upvote it. https://forum.vivaldi.net/topic/66470/create-a-separate-control-region-for-the-browser-viewport
Edit > Managed to figure out how to take a screenshot of my screenshot tool - not something I thought I'd learn today š
EhKYSvzTgT.png
You can see that the whole window is not selected, only the page, and without me having to manually select this region. Very handy! I hope Vivaldi can have this feature also.