Mouse    -----------

Left:
  click & drag - interactive rotation/translation
                 (switched by pressing keys "r"(rotation)/"t"(translation))

Wheel:
  wheel - change scale or depth
          (switched by pressing keys "s"(scale)/"d"(depth))

Right:
  not used

Keyboard -----------

a - show "about" window
c - clear, reload XML and reset view, variables
d - switch mouse mode to depth mode (mouse WHEEL)
e - invoke edit mode
l - load XML file
r - switch mouse mode to rotation mode (mouse LEFT button ) : default
s - switch to scale mode (mouse WHEEL) : default
S - save current XML data and current view into a XML file
t - switch mouse mode to translation mode (mouse LEFT button)
+ - same as up arrow (see below)
- - same as down arrow (see below)

# arrows
up    - (translation mode) move object toward up
        (scale mode) enlarge object
left  - (translation mode) move object toward left
down  - (translation mode) move object toward down
        (scale mode) shrink object
right - (translation mode) move object toward right
