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.
Say you have tabs A, B and C, and you want to have SplitView A|B but accidentally create SplitView A|C (or maybe you wanted A|C and now want to swap to A|B). The process of changing your SplitView tab configuration is 5 clicks long.
This could be reduced to 3 clicks or even 2 clicks depending on implementation
or
Either or both of these options would greatly reduce the friction of changing a splitView's current tabs.