I've been playing around with splitView for a few days now, and it's in an excellent state for a brand new feature, but there are some friction points that could do with some quality of life massages to really shine as a browser feature.
When you first open SplitView, you're presented with a list of tabs from that window which you can immediately add to that side of the view. I frequently have many tabs wit very similar names, and regularly click the wrong link, and the mistake is cumbersome to correct.
There is a lot of user input friction between getting a tab from another window into your SplitView. You have to manual move the tab to the relevant window, navigate back to the splitView tab, and then select the tab.
I understand not wanting to overwhelm users with options if they have dozens of windows open with dozens of tabs each, but there's I think there's too much friction here. Listing all the tabs for the current window first, and then listing tabs from other windows as a seporate section, so that tabs from other windows can be added to splitView directly without the need to manually move them would be appreciated.