Didn't work for me. The widget disappears when you press f12, and even if you go through the motions of keeping the mouse button pressed as you toggle between dashboard and desktop, releasing it on desktop, it still doesn't work.
Any ideas?

It worked for me... but on Leopard. Maybe this works on Leopard but not Tiger?

I don't think the poster is telling you the whole story. I suspect he/she doesn't really know how it works. Anyway, there's at least three (3) different ways you can make it work in Tiger and I'm going to give you what I believe is the easiest method as follows: goto www.versiontracker.com and do a search for DevMode Widget 1.0. Download & Install the FREE WIDGET ( DevMode Widget 1.0 ) and you'll be very happy -- it runs on Tiger like a champ. You can also then go to the developer's website and read all about it. The widget is quite simple and quite nice too. Nothing fancy but works like a charm. Good luck!

You don't have to install anything, just go to Terminal and type
"defaults write com.apple.dashboard devmode YES"
without the speech marks
and then hit return (enter)
then type "killall Dock"
This restarts your dock.
then you can use the technique posted.
Ajay