As I was going through the portal-dev section of the training materials we were asked to create an ext plugin. Later in the instructions we are asked to add a snippet into the portlet-ext.xml file (file path: docroot/WEB-INF/ext-web/docroot/WEB-INF). However, the default Portlet Application Configuration Editor will not open the xml file. Thus, I had to use another xml editor to be able to insert the snippet. I have attached what error message was received.