CX("<button id='btn-preview-refresh' "
       "data-f-preview-from='fileContent' "
       /* ^^^ fossil.page[methodName]() OR text source elem ID,
      ** but we need a method in order to support clients swapping out
      ** the text editor with their own. */
       "data-f-preview-via='_postPreview' "
       /* ^^^ fossil.page[methodName](content, callback) */
       "data-f-preview-to='#fileedit-tab-preview-wrapper' "
       /* ^^^ dest elem ID */
       ">Refresh</button>");
    /* Toggle auto-update of preview when the Preview tab is selected. */
    CX("<div class='input-with-label'>"
       "<input type='checkbox' value='1' "
       "id='cb-preview-autorefresh' checked>"
       "<label for='cb-preview-autorefresh'>Auto-refresh?</label>"