Whereas even as recently as Snow Leopard the only option we had for dragging and resizing our windows in Mac OS X was in the lower right hand corner, Mac OS X Lion brought us the ability to drag any side or corner to change window size and relative shape. Today’s tip will take this one step further with a few keys we can hold down to resize our windows more intelligently.
First up, hover your mouse cursor over the left side of a window. Any window will do, whether a Finder or Safari window. See how it changes to a little double-headed arrow? This is the default Mac OS X Lion behavior. It will do this on the top, bottom and left and right sides of any window.
Now, doing the same thing, hold down the Option key on your keyboard. As you drag the resize arrow back and forth, do you notice the difference? the Option key modifier, the window will resize on both sides equally. So, if you Option resize on the left, the right will move with it. Resize on the bottom, and the top will move along proportionally. This works on the corners, too, resizing the opposite corner in equal measure to the one you’re resizing from.
Try the Shift key, now. Hold it down while drag-resizing the left side of your test window, for example. The window resizes proportionally, sort of like when you resize an image, but keep the same proportion between the width and height of the image.
If that’s still not enough amazing, hold down the Command key to resize windows in the BACKGROUND. Yes, I said background, and put it in all capital letters. Because, seriously? That’s pretty cool. Apparently this has been available before OS Lion, but makes a lot more sense when you can resize any edge of a window.
There’s another little trick you can mess around with, too. When you move your cursor over the left or right edges, you get a horizontal arrow. If you click and drag in the vertical direction, you’ll actually move the window, which may help if you need to move it without using the title bar. The same behavior holds true if you hover over the bottom, getting a vertical arrow, and click and drag horizontally. Sweet, huh?
Source: Mac OS X Tips
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