code: function adjustPanes(x, y, overPreview) {
      var ratio = isLeftRight ?
          (x / $outer.clientWidth) :
          ((overPreview ? y : y - 25) / ($outer.clientHeight - 25));
      var psize = overPreview ? editorSize + ratio * 100 : ratio * 100;
      if (psize >= 0) { resizeEditor(psize); }
    }
docs: draggable pane adjuster x and y come from the mouse either over the preview or the editor preview coordinates start at the separator (==> editorSize + ratio) allow 25 pixels for the header (should be read from element)