Using the built-in plugin of the browser to show the PDF files (i.e., using the NavigateUrl
property set to a PDF file) is a feature taht is entirely controlled by the browser plugin. When an iframe element (the RadWindow) is loaded with a PDF file, the DOM (window.document) is not available with the well known DOM events, therefore there is no available client-side API that could let you control the user actions happened on window (the browser window) loaded with a PDF content.
On a side note, there is the pdf.js
library that is commonly used to render PDF files in the browser using an entirely third-party client-side library. More about integrating this library with the Telerik controls explained and demonstrated in this blog post
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