How To Use OS X El Capitan's Split Screen Mode
Windows users may have been able to lock two windows into a split screen mode for years, but that feature has now made it to the Mac with OS X El Capitan. The operating system update introduces support for this screen-tidying feature for up to two windows per display at a time. You can browse recipes online in Safari with a to-do list open in Notes to make a grocery list, or you can have Steam and Twitter open side by side to get tips for what to buy in the latest sale. Here's how to divide your screen equally (or unequally) between two windows.
How To Use OS X El Capitan's New Split Screen Mode
1. Click and hold the green button in the upper left corner of an app that shows two triangles pointing in opposite directions. Do not release the button. If the green dot reveals a + sign, that app does not support slit screen view.
2. While holding down on the button, drag the window to the half of the screen you want to place it in. That half of the screen will be tinted blue.
3. Click on the window you want to fill the rest of your screen.
4. To resize the windows, click and drag the black bar between the two windows to the left or right.
5. To break a window out of split screen view, move your cursor to the top of the window and click on the green dot again.