Before OS X Lion, you resized a window by clicking the green circle in the upper-left corner of the window or by dragging the lower-right corner of the window up or down, side to side, or diagonally. These methods worked fine for adjusting the basic size of a window, but you often had to combine the resizing with some other moving of the window to get everything just the way you wanted. Over the years, Apple has made some changes to the methods for resizing windows.

With OS X Lion, Apple took the plunge and introduced the ability to resize windows on a Mac by dragging any side or corner. This simple modification lets you adjust the size of a window by expanding or shrinking only the side of the window that needs a little adjustment. For example, if a window has some content just past its right edge, drag the right edge of the window to reveal its entire contents.

Move your cursor to any side of a window: top, bottom, left, or right. As the cursor approaches the edge of the window, it changes to a double-sided arrow. When you see the double-sided arrow, click and drag to resize the window.

Resizing also works on the corners of a window. Move your cursor to any corner to produce the double-ended arrow. Then click and drag. Holding down the Option key while dragging either side or corner will keep the window centered in its location.