This menu command starts the Zooming.
You can zoom the drawing area two, three or four times directly from menu or by setting an user zoom factor in a zoom dialog box.
The Horizontal to window menu item searches the maximum possible zoom without horizontal scroll bar, the Vertical to window menu item searches the maximum possible zoom without vertical scroll bar (Notice: These two menu items can be used only if you have checked the Proportional Aspect Ratio item in the Options menu).
The Selected to window menu item invokes the zooming along the selection rectangle. If the Dynamically Zoom Switch in the Options menu is activated, then this zooming is started automatically as soon as the selection rectangle is defined.