Combo(attached to a popup) gets hided when clicked

I have a combo loaded with more than 100 records.
Now the problem is combo gets loaded perfectly with data even filtration can be performed, but when clicked on the combo it gets disappeared. Can somebody help me out on this, Below is the sample code which I tried.

 myPop = new dhtmlXPopup(); //style="height:200;width:250  style="overflow:scroll;"

myPop.attachHTML(‘

’);
myPop.show(180,-420,400,450);
combo=new dhtmlXCombo(“div1”,“pgmid”);
combo.enableFilteringMode(true);
var xmlstring=getEventId();
combo.loadXMLString(xmlstring);
// combo.allowFreeText(false);
combo.setFocus();
combo.attachEvent(“onChange”, function(value, text){
myPop.unload();
myPop = null;
init();
loadform(value);
});



Hello
Please attach completed demo with steps of reproducing on support@dhtmlx.com with link to this topic
By the way method loadXMLString is deprecated from 4+ version