下拉框模拟只读

//根据下拉框ID设置下拉框只读
function setReadOnly(obj_id){
var obj = document.getElementById(obj_id);
obj.onmouseover = function(){
obj.setCapture();
}
obj.onmouseout = function(){
obj.releaseCapture();
}
obj.onfocus = function(){
obj.blur();
}
obj.onbeforeactivate = function(){
return false;
}
}





AAAAAAAAA
BBBBBBBBB
CCCCCCCCC
DDDDDDDDD



setReadOnly("span_select");

this.ddlSysCategory.Attributes.Add("onfocus","this.blur();");
this.ddlSysCategory.Attributes.Add("onbeforeactivate","return false");
this.ddlSysCategory.Attributes.Add("onmouseover","this.setCapture()");
this.ddlSysCategory.Attributes.Add("onmouseout","this.releaseCapture()");