How to close CalendarExtender on lost focus or mouse out

<script language="javascript" type="text/javascript">    var blnflag = false;    document.onmouseout = function(sender, args)    {       if (event.srcElement.tagName.toLowerCase() == "div" && event.srcElement.outerHTML.indexOf("ajax__calendar") > 0) blnflag = true;       if (blnflag && event.srcElement.tagName.toLowerCase() != "div")       {          blnflag = false;          $find("CEBID1").hide();       }    } </script> <asp:TextBox id="txtFrom" onkeypress="return false;" onkeydown="return false;" onmouseover="return false;" runat="server" style="width: 100px" /> <img id="img1" runat="server" alt="Date" src="images/cal.gif" temp_src="images/cal.gif" /> <cc1:CalendarExtender BehaviorID="CEBID1" runat="server" ID="cl1" TargetControlID="txtFrom" PopupButtonID="img1" Format="dd-MMM-yyyy"></cc1:CalendarExtender>