Event not fire when I press enter key instead of clicking on a RadButton

[Hee]

<script type="text/javascript">
        function pageLoad() {
            $find('<%= RadButtonClickTest.ClientID %>').focus();
        }

        function RadButtonClickTest_OnClientClicking(sender, args) {
            args.set_cancel(!confirm("Are you sure cancel?"));
        }
</script>

<div>
        Has fired server side event?: <asp:Label ID="LabelTest" runat="server" Text="No"></asp:Label>
        <telerik:RadButton ID="RadButtonClickTest" runat="server" Skin="Simple" Text="Cancel" UseSubmitBehavior="false" TabIndex="1" OnClientClicking="RadButtonClickTest_OnClientClicking" OnClick="RadButtonClickTest_Click" />
</div>

We updated telerik version to v2013.1.417 for our site.
And then we got big problems with RadButton.
When I press enter key instead of clicking on a RadButton, there are two problems like below.

1. If I select "OK" at confirm window, it doesn't fire server side event even if AutoPostBack=true.
2. If I select "Cancel" at confirm window, first time, it is work successfully. But if I press enter key on a RadButton again, Client side event does not fire and server side event fire directly.

I don't understand this problem. You can download full test source from below link.
http://www.mediafire.com/?80q15q2hk6surq4
Please refer to it.
Our site have a lot of RadButton. So this problem is so big issue.
What's the problem with RadButton?

Thanks
Hee

[Danail Vasilev]

Hello Hee,

This seems to be an issue with the control. I have raised its priority and logged it as a feedback item here, so that you can monitor, comment or vote on it.

As a small token of gratitude for reporting this issue I have updated your Telerik points.

Kind regards,
Danail Vasilev
the Telerik team