IceDragon & Silverlight

I have Microsoft Silverlight installed on my system, but IceDragon is not recognizing (it’s not showing up in the plugins tab under add-ons) it and I therefore cannot properly view pages that require it, like Straight-Line Diagrams Online GIS Web Application . Any idea why?

  1. its deprecated
  2. only patches, security fixes for Silverlight 5 till OCT 2021
    Silverlight is no longer supported in Google Chrome since September 2015,[8] and in Firefox since March 2017 or version 52 as of the latest update.