Was it incorporated into the editor?
Yes. At best, you should use a nightly for this.
There are two modes: split view and "docked":
1.) Split view means to split a file either horizontally or vertically, i.e. via the context menu of the editor. This shows the
same file just splitted (but synchronised).
2.) The "docked" mode is if you undock an editor window clicking on the editors tab and by dragging it away (tear-off). Then, if you come to any border, you can dock- it in again. Thus, you can have as many
different editors side-by-side, or under each-other or ion any layout you like. Just as you dock e.g. the manager window, too.