X-Ray mode displays the underlying geometric skeleton of a selected form. In this mode, surfaces become transparent, allowing you to more directly interact with the individual elements that comprise the form. This mode is useful when you need to understand how a form is constructed, or when you need to select a specific part of the form element for manipulation.
X-Ray mode is available for only one form at a time in all model views. For example, if several, tiled views are displayed and you use X-Ray mode for a form in one view, the other views display X-Ray mode as well. Likewise, switching X-Ray mode off in one view switches it off in all others.