firefox & png

[david coder]

is there a system png that comes w/ 8.3 that is distinct from the ports png?
if not, how explain that install of firefox-14.0.1 fails w/ the error message
that the system png does not support APNG even though the makefile for the
png port contains the line

	OPTIONS=        APNG "Animated PNG support" On

?

i am puzzled.

thx.  

david coder