This is very miscellaneous feature. To turn mouse emulation on, press key
'M'. Arrow keys now move mouse cursor, keys <Enter> and 'L' work as left mouse
button, key 'R' as right mouse button. To speed up moving cursor, press <Ctrl>
key, and to slow down it press <Shift>.
In this mode, it is possible to use other keyboard keys as it is described for
it. To turn mouse emulation mode off, press key 'M' again.
Note: when you switch to another application, mouse emulation does not work. But when you return to the Zoomer again, it continues working as earlier. If you activated a menu, mouse emulation also is temporary off, until you've finish working with the menu, so you can use arrow keys to navigate in menu as usual.