I am using webtool for my daily work, but after upgrading to 11.0 version, it does not work properly now.
It does not support java
We recently blocked old versions of the Java plugin because they made people's computers vulnerable to attacks. If you update Java it will work in Firefox.
Instructions for updating Java and re-enabling it in Firefox are here - Old versions of Java have been blocked - update and unblock Java
More info on why we blocked Java is here - http://blog.mozilla.org/security/2012/04/06/why-an-outdated-java-plugin-is-so-serious/