When exporting a document with the new (and very nice !!) "export to pdf" 
function, the background of an automatically generated index table is gray in the 
pdf file. The index table is a non editable field, like let's say page numbers. Within 
the OO doc they have a gray background to indicate, that they are actually a 
field. When printing directly to a printer or to a postscript file the background of 
all fields is white (as set in the background properties). When using export to pdf 
the background of all other field types is white as well. Only the index table get a 
gray background. 
 
Juergen