title: jqGrid column header display slows down when scrolling horizontally
body: <p>I am using <code>jqGrid</code> with a horizontal scrollbar, but when I use the horizontal scrollbar the column header does not move together with the columns. Once I stop scrolling the grid comes back to normal. See the attached picture:
  <img src="https://i.stack.imgur.com/GC5OG.png" alt="enter image description here"></p>
  
  <p>This is happening in FF (4.0.1) but not in IE8.</p>
  
  <p>Here are the grid options I use:</p>
  
  <pre><code>width:'800',
  shrinkToFit:false,
  height: 500,
  pager: '#pagerDiv',
  gridview: true,
  rowNum: 50,
  rowTotal: 500,
  sortorder: 'desc',
  cellEdit: true,
  cellsubmit: 'remote',
  cellurl: 'MyURL',
  beforeSaveCell: 
  function (rowid, cellname, value, iRow, iCol) {
      return parse(value);
  },
  viewrecords: true,
  loadComplete: loadCompleteHandler,
  ignoreCase: true
  
  ....
  
  jQuery(function(){
          jQuery("#listTable").jqGrid('filterToolbar',{
                              stringResult: true,
                              searchOnEnter: false });
      });
  </code></pre>
  
  <p>I have <code>jqGrid</code> version 3.8.2, <code>jQuery</code> 1.4.4 (full).
  Is there any way to fix this?</p>