dhtmlxCombo as a filter

Suite 7.0/6.0/5.0 and Optimus Suite 5.0
#1

how to get the value # combo_filter ?

var v1 = mygrid.cells(#combo_filter).getValue()
document.getElementById(“filter1”).value= v1;

<link rel="STYLESHEET" type="text/css" href="../../codebase/dhtmlxgrid.css">
<link rel="stylesheet" type="text/css" href="../../codebase/skins/dhtmlxgrid_dhx_skyblue.css">
   <link rel="STYLESHEET" type="text/css" href="../../../dhtmlxCombo/codebase/dhtmlxcombo.css">
<script  src="../../codebase/dhtmlxcommon.js"></script>
<script  src="../../codebase/dhtmlxgrid.js"></script>
<script  src="../../codebase/ext/dhtmlxgrid_srnd.js"></script>
<script  src="../../codebase/ext/dhtmlxgrid_filter.js"></script>    
<script  src="../../codebase/dhtmlxgridcell.js"></script>
<script  src="../../../dhtmlxCombo/codebase/dhtmlxcombo.js"></script>
  
<div id="gridbox" style="width: 600px; height: 270px; background-color:white;"></div>
<script>
dhx_globalImgPath = "../../../dhtmlxCombo/codebase/imgs/";
mygrid = new dhtmlXGridObject('gridbox');
mygrid.setImagePath("../../codebase/imgs/");
mygrid.setHeader("Sales,Book Title,Author,Price,In Store,Date of Publication");
mygrid.attachHeader("&nbsp;,#combo_filter,#combo_filter,&nbsp;,#cspan,#cspan");
mygrid.setInitWidths("50,150,120,80,80,80");
mygrid.enableAutoWidth(true);
mygrid.setColAlign("right,left,left,right,center,left");
mygrid.setColTypes("dyn,ed,ed,price,ch,ro");
mygrid.setColSorting("int,str,str,int,str,str");
mygrid.setSkin("dhx_skyblue");
mygrid.init();
mygrid.enableSmartRendering(true);
mygrid.loadXML("../common/500.xml");
</script>
#2

To get filter element you can use the following approach
var combo = grid.getFilterElement(index) /1 or 2 in your sample/

and getActualValue() returns value of dhtmlxCombo:

var value = combo.getActualValue();