public string OnPopupOpening { get; set; }

Public Property OnPopupOpening As String
	Get
	Set

public:
property String^ OnPopupOpening {
	String^ get ();
	void set (String^ value);
}

member OnPopupOpening : string with get, set

Property Value

There can be some conditions you do want not to open the calendar popup on click of the popup button. Then you should cancel the event either by return false; or set its argument args.CancelOpen = true;

            <script type="text/javascript">
function Opening(sender, args)
{
    args.CancelOpen = true;
    //or
    return false;
}
</script>
<kaxCln:KaxDatePicker ID="KaxDatePicker1" runat="server">
    <ClientEvents OnPopupOpening="Opening"/>
</kaxCln:KaxDatePicker>
                

Set the args.CancelSynchronize = true; to override the default DatePicker behavior of synchronizing the date in the DateInput and Calendar controls. This is useful for focusing the Calendar control on a date different from the DateInput one.

            <script type="text/javascript">
function Opening(sender, args)
{
    args.CancelCalendarSynchronize = true;
    sender.Calendar.NavigateToDate([2006,12,19]);
}
</script>
<kaxCln:KaxDatePicker ID="KaxDatePicker1" runat="server" >
    <ClientEvents OnPopupOpening="Opening"/>
</kaxCln:KaxDatePicker>
            

            [AspNet/ASCX]        
            

            <script type="text/javascript">
function OnPopupOpening(datepickerInstance, args)
{
   ......
}
</script>

<kaxcln:KaxDatePicker ID="KaxDatePicker1" runat="server">
   <ClientEvents OnPopupOpening="OnPopupOpening" />
</kaxcln:KaxDatePicker>
            

Reference