When you surf onto a Yahoo! Internet Web site or open the Yahoo! Messenger chat software, you probably give more thought to where you're going or saying than how things look on the screen. To tidy up how windows pile on top of each other or to make the screen more organized, you can fit Yahoo! exactly to your screen. Not having free-floating windows makes it less likely that you'll unintentionally click on something, and sizing Yahoo! to fit also gives everything on the screen equal real estate space as it competes for your attention.
Open an Internet browser; if Yahoo! is not your home page, enter it in the Web site bar at the top of the screen and press "Enter."
Click the "Mail" link on either the left or right portion of the screen, or leave Yahoo! as the home page on the screen.
Click the small hollow box icon in the top-right corner of the monitor – it is between the icon of a dash (-) and an "X." The Yahoo! page should fit exactly to the computer screen. If it doesn't, click the hollow box icon again.
Resize the Yahoo! Messenger window to fit your screen by clicking the hollow box in the pane's top-right corner. Messenger switches to extend or shrink to fully fit the vertical length of your screen.
Resize the Messenger pane to custom fit your screen by clicking the hollow box in the top-right corner so that the pane is shorter than the vertical length of the monitor -- that is, not stretched to fit. Click the left or right border of the Messenger pane. Drag the border to the left or right, widening it so that it takes up the entire screen size. Adjust the opposite side's border. Adjust the height by clicking either the top or the bottom border and then stretching to fit.