You could hack this by using a couple Panels.
Example
<%@ Page Language="C#" %>
<%@ Register Assembly="Coolite.Ext.Web" Namespace="Coolite.Ext.Web" TagPrefix="ext" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>Coolite Toolkit Example</title>
<style type="text/css">
.blue {
background-color: #DFE8F6;
border-bottom: solid 1px #99BBE8 !important;
}
</style>
</head>
<body>
<ext:ScriptManager runat="server" />
<ext:Panel runat="server" Width="350">
<Body>
<ext:ContainerLayout runat="server">
<ext:Panel
runat="server"
Header="false"
Border="false"
Cls="blue">
<Buttons>
<ext:Button runat="server" Text="New" />
<ext:Button runat="server" Text="Delete" />
</Buttons>
</ext:Panel>
<ext:Panel runat="server" Height="185" Html="Content" Border="false" />
</ext:ContainerLayout>
</Body>
</ext:Panel>
</body>
</html>
Just an option that might work for you.
Note: the <Buttons> collection will only render and accept <ext:Button> controls.