+1 for tabs.
I think it’s much more accessible.
While we’re on the topic, I’d really like to see the Page Settings go back to a tab on the right. I don’t like them covering up the tree when I don’t need them and I found it really disorienting to have them pop up there at first. I think it will be *much* easier for new users to get comfortable with the UI if there’s nothing at the left except the resource and element names.
Page settings - I agree it’s good having them visible, but it does mean the page tree is no longer visible.
What about a collapsible panel for page settings in a column on the RIGHT side of the screen? Then you can have both page settings and the document tree visible.