Scale Window...
  The Scale Window...  menu item allows you to modify the
  proportions of the visible portion of the canvas.
  To scale the visible portion of the canvas:
                                Note
      You cannot undo this operation.
  1.  Choose Scale Window...  from the Edit menu.
      Paint displays the Scale dialog box.
  2.  For both the x scale and the y scale, click on one of
      the percent buttons to change the scale.  For example,
      clicking on 25% reduces the selected area to one-fourth
      the original size, while clicking on 200% makes it twice as
      large as the original.
      To specify your own percentages, enter a number less
      than 100 to shrink the figure or a number greater than
      100 to expand the figure.
  Additional topics:
  *   Using Menus and Controls
  *   Edit Menu
  *   Overview of Paint