.igdd_QuickQubeDropDownListContainer{
Width:100%;
}
Hi, ashpawan.
It has been some time since your post but in case that you still need assistance I will be happy to help.
You can set the width of the WebDropDown to 100% and then the size of the DropDown Container:
WebDropDown1.DropDownContainerWidth = 200;
WebDropDown1.DropDownContainerHeight = 300;
You can also set these values according to the size of WebDropDown’s parent container.
More information can be found here: http://help.infragistics.com/NetAdvantage/ASPNET/2011.2/CLR4.0/?page=WebDropDown_Setting_Height_and_Width_of_DropDown_Container.html
Please let me know if this helps.