Once Apple gave us Full Screen mode, the next step—new in El Capitan—was obvious: split Full Screen mode. In this arrangement, two windows fill the screen, edge to edge and top to bottom. Just as in Full Screen mode, the menu bar, Dock, and all other cluttery extras are hidden to maximize screen space; the only difference is that two apps are now sharing that big monitor canvas.
This combination works very well when you want to keep a continuously updating app visible—Twitter, Mail, or FaceTime, for example—while continuing to do work in a second app. It’s also handy when you’re referring to one app (a recipe in your web browser) and making notes in another (an ingredients list in Notes).
Once again, though, Split Screen doesn’t work in all apps—only the ones that work in Full Screen mode, as described above.
There are two ways to get in and out of Split Screen mode, but this one is quickest:
Click-and-hold the green button at the top left corner of Window No. 1. (See Figure 5-9, top.)
The weirdest thing now happens: Whichever half of your monitor contains this window (usually the left side) becomes shaded blue (Figure 5-9, second from top). That’s El Capitan’s way of telling you: “When you release your mouse or trackpad, this window will snap to fill only this half of the screen.”
At this point, you could, if you liked, drag the ...