That's not the source of my problem, since I'm using either GTK+2.4 or 2.6.
The pushed-in buttons are now somewhat distinguishable from the ones that aren't
pushed in (originally it was almost impossible to tell whether a button was
pushed in) but it still isn't as easy to tell which ones are pushed in as it
is in 5.7.  In 5.7, I could just glance at a button to tell whether it was
pushed in.  Not so in 6.0.  I think the source of the problem is that in 5.7, 
there is a border that gives the buttons a more 3-D look when pushed in.

To see what I'm talking about, run 5.7 on a Solaris SPARC host and run 6.0 on
that same host and compare how easy it is to tell at a glance which buttons
are pushed in.

The current implementation is *possibly* acceptable, but is a step backwards
from what we had in 5.7.