Widgets, Gadgets or Modules are very common and powerful feature of Web 2.0 applications. It converts single loaded page in the browser to multi-threaded application. It allows end user to work on multiple little utilities and windows from one page. Widget framework is supported by various Ajax libraries and lot of code is getting created by developers to allow this feature. Once framework is in place various different users can leverage APIs and libraries to develop their own little widget and deploy on the application domain. Any user of the application can register that widget and start utilizing its feature. This scenario opens up possibility of Cross Widget DOM Spying. This paper is going to describe that scenario and its understanding.
Read here