As founder and CEO of Stilesoft, Adam Stiles has marketed the NetCaptor software as an IE browser for power users. NetCaptor, which uses Microsoft's IE rendering engine to provide browser tabs and other comparatively advanced features, has capitalized on the fact that IE hasn't gotten an all-around feature upgrade in more than three years. But now Stiles and other vendors of third-party browser applications that piggyback on the Microsoft browser are concerned that <A HREF="http://news.zdnet.com/2100-3513_22-5401068.html?tag=zdnn.alert">IE's widely noted stagnation</A> may be proving as much a liability as an opportunity.