g3view displays a group 3 fax file in an X11 window.  The input file
must be a raw, single-page fax received by a fax modem.
The fax image is rendered at full resolution and then successively
scaled down by a linear factor of 2 prior to display until it fits on
the screen.  The display can be controlled interactively using mouse
and keyboard commands.  The left mouse button expands the image by a
factor of two and the right button reduces it by the same factor.  If
the image is bigger than the available window size, the middle mouse
button can be used to reposition it within the window.  To see the
right bottom corner of the image, click near in the right bottom
corner of the window, etc.