[JangoSteve]

The author mentions a bunch of programs that offer similar functionality but states that "the way they're designed doesn't work for me." I'd be curious what about them doesn't work.

I use TotalFinder primarily for this functionality, and their split-pane looks almost identical to what he has set up in the screenshot, with the added benefit that it is more efficient (e.g. you can move the window around and resize it and the panes stay together, you can adjust the size of each pane relative to the other just by dragging the single middle bar, etc.).

TotalFinder split-pane screenshot: http://i.imgur.com/K6KkSws.png

[stelian]

The tab join looks weird(aesthetically) and the separator is too thin. I want one side in focus. But all these things have to do with taste. The screenshot you attached looks probably great to you, but I prefer the side by side windows.

[milesf]

I prefer TotalFinder as well, along with Divvy with a shortcut to quickly resize. I hit Command-T to create a new tab, then Command-G to connect them together. It's now just muscle memory for me, I don't even think about it.