If you click on the Zoom
icon, you can mark an area on the
screen and magnify it to fill the entire window. First, click on the
Zoom
icon; the mouse pointer will turn into a magnifying glass.
Next, use the magnifying glass to draw a box the same way that you
would draw a frame: So click the left mouse button once to set the
first corner and a second time to set the diagonally opposite corner.
You can abort the operation by clicking the right mouse button.
Note: Since you can click on the window's scroll bars during this operation, you can define an area that is larger than the window itself. This way you can also shrink the display by any desired amount.