We love your widget, and would like to use it on all of our clients' sites, however it does have a validation error:
& did not start a character reference. (& probably should have been escaped as & amp;)
I was able to fix it very simply by going into the code editor and replacing any instances of "&" in the share URLs with its ascii character code. Would it be viable for you to include valid URLs in a future update?
(And I love your icons, but it would be really nice to have the option of using custom icons and changing the icon size if the client prefers a different style.:))