Hi,

I found the answer myself but not sure if efficient.

I hooked the following ClientEvents "SelectionChanged", "DropDownClosed", "DropDownOpened". In DropDownOpened, I make all items to be selected if "ALL" is selected. In DropDownClosed, I make all items unselected EXCEPT "ALL". So, even in Postback the only "ALL" is displayed.

In case if it helps someone., here goes the code

function wdd_dropDownOpened(sender, eventArgs) {
    var items = sender.get_items();
    if (items.getItem(0).get_selected() == true && items.getItem(0).get_text().toUpperCase() == 'ALL') {
        for (i = 1; i < items.getLength(); i++) {
            var item = items.getItem(i);
            item.select();
        }
    }

} // -->
function wdd_dropDownClosed(sender, eventArgs) {
    var activeIndex = sender.get_activeItemIndex();
    var items = sender.get_items();
    if (activeIndex == 0 && items.getItem(0).get_selected() == true) {
        sender.set_currentValue("ALL", true);
        for (i = 1; i < items.getLength(); i++) {
            var item = items.getItem(i);
            item.unselect();
        }
    }

}
function selectedIndexChanged(sender, eventArgs) {
    var activeIndex = sender.get_activeItemIndex();
    var items = sender.get_items();
    if (activeIndex == 0 && items.getItem(0).get_selected() == true && items.getItem(0).get_text().toUpperCase() == 'ALL') {
        for (i = 1; i < items.getLength(); i++) {
            var item = items.getItem(i);
            item.select();
        }
    }
    else if (activeIndex == 0 && items.getItem(0).get_selected() == false && items.getItem(0).get_text().toUpperCase() == 'ALL') {
        for (i = 1; i < items.getLength(); i++) {
            var item = items.getItem(i);
            item.unselect();
        }
    }
    else if (activeIndex != 0) {
        if (items.getItem(activeIndex).get_selected() == false) {
            items.getItem(0).unselect();
        }
    }
}

Ok, i have 2 questions now..

1. Is the above method efficient? Any other workarounds?

2. I have around 15 ASPX pages, can I create a Custom control to include the above Javscript to avoid repetitive code? Please suggest.