Cocoa reminds me of Frontier
In some ways Cocoa reminds me of Frontier in that there’s (usually) an easy way to do something and then lots of hard ways to do something.
The problem is that the easy way is not always obvious. The other problem is that I forget the rule that says, “If you’re standing on your head to do something, look for the easy way.”
So I was looking all over for how to set up an NSSplitView—a split window, like that used by most email apps. I couldn’t find anything. There’s no NSSplitView in Interface Builder’s widget pallete.
Then finally I noticed that I could do it via the “Make Subviews of” submenu of the Layout menu. It was so easy. And of course it just plain works.