Use the XML Preview page to specify style sheets to transform the XML. The appropriate style sheets enable you to get a useful preview for files of this XML file type.
You can also specify any other files that might be needed, for example CSS files.
For more information about using style sheets to transform XML, see for example, www.w3schools.com/xsl/xsl_intro.asp
If you do not provide any style sheet transform files, Studio displays the standard tree view of the XML file.