> Lightbulbs are driven in a similar way but respond more slowly, of
> course, and should have pre-heat current applied even when nominally
> off, to avoid thermal shock from destroying the bulb.

Note that because lightbulbs are not diodes, current may flow through
unexpected paths; your best bet is probably to try to bias inactive
rows at 1/3 voltage and inactive columns at 2/3 voltage; this will ensure
that all the inactive lights are at 1/3 voltage (regardless of what else
is on the same row/column).  Note that if the lights only get 1/3 voltage
they will be using only about 1/9 the power of "full on" lights and will
consequently glow much more dimly (if at all).