gdk convert called when not needed?

hi,

i am getting some strange behavior from Mozilla 1.6 on a Solaris 8
machine. I have 2 displays: 0, which is a 24-bit true color display and
1 which is 8-bit pseudo color. I have recompiled the GTK+ 2.1.0 library
(the same version that shipped with the particular Mozilla I am using),
modifying the function rgb_convert_8_d() in gdkrgb.c, so that the
colors are scrambled and "hi there" is printed out to the console every
time it is called. On display 1, I get the expected results--well,
almost: the colors are scrambled for all the widgets in the browser
frame and all images displayed within its client area, but text and
background colors display normally).

The strange part is that on display 0, the modified rgb_convert_8_d()
gets called as well, even though all the images and widgets are
displayed in 24-bit true color!

does anyone have an explaination?