public string OnClientDropDownOpening { get; set; }

Public Property OnClientDropDownOpening As String
	Get
	Set

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

member OnClientDropDownOpening : string with get, set

Property Value

Use the OnClientDropDownOpening property to specify a JavaScript function that will be executed prior to dropdown item opening - either by left-clicking it with the mouse or hitting the down arrow after tabbing to that item. You can cancel that event (prevent dropdown opening) by seting the cancel property of the event argument to true.

Two parameters are passed to the handler

• sender (the client-side KaxToolBar object)
• eventArgs with three properties
  • item - the instance of the dropdown item being opened
  • cancel - whether to cancel the event
  • domEvent - the reference to the browser DOM event (null if the event was initiated by calling a client-side method such as dropDownItem.showDropDown();)

<script language="javascript">
function clientDropDownOpening(sender, eventArgs)
{
var toolBar = sender;
var dropDownItem = eventArgs.get_item();

alert("You are opening the '" + dropDownItem.get_text() + "' dropDown in the '" + toolBar.get_id() + "' toolBar.");

if (dropDownItem.get_text() == "Align")
{
alert("Alignment is not available");
eventArgs.set_cancel(true);
}
}
</script>

<kettic:KaxToolBar id="KaxToolBar1" runat="server" OnClientDropDownOpening="clientDropDownOpening">
<Items>
<kettic:KaxToolBarButton Text="Left"></kettic:KaxToolBarButton>
<kettic:KaxToolBarButton Text="Center"></kettic:KaxToolBarButton>
<kettic:KaxToolBarButton Text="Right"></kettic:KaxToolBarButton>
<kettic:KaxToolBarDropDown Text="Align">
<Buttons>
<kettic:KaxToolBarButton Text="Left"></kettic:KaxToolBarButton>
<kettic:KaxToolBarButton Text="Center"></kettic:KaxToolBarButton>
<kettic:KaxToolBarButton Text="Right"></kettic:KaxToolBarButton>
</Buttons>
</kettic:KaxToolBarDropDown>
<kettic:KaxToolBarSplitButton Text="Right">
<Buttons>
<kettic:KaxToolBarButton Text="Left"></kettic:KaxToolBarButton>
<kettic:KaxToolBarButton Text="Center"></kettic:KaxToolBarButton>
<kettic:KaxToolBarButton Text="Right"></kettic:KaxToolBarButton>
</Buttons>
</kettic:KaxToolBarSplitButton>
</Items>
</kettic:KaxToolBar>

Reference