Previously, the thumbnail on the page must be used to use a third party component. Now, with .NET, thumbnails can be easily implemented. Below is an example of achieving thumbnails.
<% @ Page language = "c #" codebehind = "TOTHUMBNAILIMAGE.ASPX.CS" src = "TOTHUMBNAILIMAGE.ASPX.CS" autoeventwireup = "false" inherits = "exam_c.tothumbnailimage"%>