[caret-users] Why does lighting and opacity selection not make any difference?

[Yune S. Lee]

 Dear caret users,
 I have a trivial question regarding lighting and opacity in the 
overlay/ underlay-surface .
 I've been playing around with lighting (check or uncheck) and opacity 
values to see what's changing in the graphic, but I didn't notice any 
difference in my workstation.  So, I wonder why this happens and what I 
am supposed to see depending on different setting (e.g., what would have 
happened when lighting
is unchecked?) Any help would be appreciated.

 thanks,
 YSL