Change hover color of scrollbar thumb via skin customization

Hi,

Over in opera.general, Lee Harvey gave me some great leads in
customizing the skin to change the scrollbar shuttle hover color. 

http://operawiki.info/AdvancedSkinGuide
http://operawiki.info/SkinINIChanges
http://operawiki.info/GuideScrollbarhorizontal
http://operawiki.info/Opera7Skinning
http://my.opera.com/community/forums/forum.dml?id=28


But I can't find any reference to hover in the skin.ini file in
standard_skin.zip. Nor have I come across a yellow .png file that
could the intended target. I'm sure there's an easy way to do
this. Insight would be appreciated.

Thanks,