So just a quick little blog post for a Friday about a small variation I found the other day while working on a SharePoint web part. We had a need for our web part to display Silverlight and have a transparent background as well as a div floating over the Silverlight. So I wrote a quick little visual web part that included the div and displayed the .xap file. The web part worked fine in Safari and Chrome on the Mac, and IE, Safari and Chrome on Windows, but the .xap file wouldn’t load in Firefox on either platform.

So, I resorted to Google and found this post – apparently, for any browser based on Firefox, when you declare data=”data:application/x-silverlight-2″ within your object, you need to include a , at the end of the string.

I updated my code to check the browser and then use data=”data:application/x-silverlight-2,” for Firefox and to use data=”data:application/x-silverlight-2″ for any other browser. As soon as that fix was in place on my web part, the Silverlight loaded fine across all the browsers and both platforms.