Hi:

I'm using Gnome-Shell 3.0.1 and using gnome-shell-extension-tool builded a sample extenion: the one that when you click on the panel show a Hello World!
And it is not loading the css, I mean I'm getting just the 'Hello World!' text with no border, and background-color and nothing else.

When I moved the extension completely to /usr/share/gnome-shell/extensions then it worked right.

Step to reproduce it
1.
$ gnome-shell-extension-tool --create-extension
name: sample-click
desc: sample click
uuid: default@default
2.
Gnome-Shell restarted, the extension was loaded and when clicking in the panel, it shows just the text without the css properties.
3.
Move the extension to /usr/share/gnome-shell/extensions
$ mv .local/share/gnome-shell/extensions/sample-click@dedault.sample.click /usr/share/gnome-shell/extensions/
4. 
Gnome-Shell restarted, the extension was loaded and when clicking in the panel, it shows the text and the box surrounding the text.