Recent gconf-editor settings
gconftool-2 --type int --set /desktop/gnome/thumbnail_cache/maximum_age "-1"
Cannot make setting stick. I can change the setting if the integer is a positive number but it will not resort to MINUS number
It's a little tricky setting negative values with gconftool, you need to prepend with
So for your example
Nope this might still not work. I suggest you to Download Dconf. Its the newer version of Gconf. See I dont know much about these. But few days back when my login sound was not working I frist tried to reset a sound value using Gconf but after logout the value were lost. After that I tried Dconf and It worked !!!
I think Gconf is for old apps and Dconf is for newer One.