[sugar] Trying to create an activity icon

[Gonzalo Delgado]

 Hello there again. Dispite my lack of artistic skills, I'm trying to
create an icon for the activity I'm working on. I did a very basic one
using Inkscape and following the specifications from the wiki, but I
can't get it to change colors when the mouse cursor is over it. I even
tryied modifying the TamTam icon, then adding the lines :

<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd" [
  <!ENTITY fill_color "#FFFFFF">
  <!ENTITY stroke_color "#000000">
]>

with a text editor (excuse me if this is lame, I just never had to do
this sort of thing), but then the mose-hover-effects are gone :(

Any clues?
Thanks!!

-- 
Gonzalo Delgado.