On the standalone version, the frame code of the xFormsManager is actually in a jsp UI-FW, tasks.jsp, which is wrapping everything.
Note that the header of UI-FW, siteheader.jsp is also responsible for the layout of the whole page.
In the portlet version, the form pops up in a ExtJS frame. The javascript can be found in entry.js and the code calling it is defined in the ExtJS table, found in ui-fw-portlet.jsp
