Here's my markup:

<ext:FitLayout ID="FitLayout1" runat="server">
    <Items>
        <ext:Panel ID="grid" runat="server" Layout="Card" ActiveIndex="0" Border="false">
            <TopBar>
                <ext:Toolbar ID="Toolbar1" runat="server">
                    <Items>
                        <ext:ToolbarFill ID="ToolbarFill1" runat="server" />
                        <ext:ComboBox ID="ViewBy" runat="server" SelectedIndex="0">
                            <Items>
                                <ext:ListItem Text="Account" Value="0" />
                                <ext:ListItem Text="Asset Type" Value="1" />
                            </Items>
                            <Listeners>
                                <Select Handler="refreshClientHoldingsGrid();" />
                            </Listeners>
                        </ext:ComboBox>
                    </Items>
                </ext:Toolbar>
            </TopBar>
            <Items>
                <ext:Panel ID="AccountsPanel" runat="server" Border="false" Layout="Fit">
                    <Items>
                        <ext:TreeGrid ID="AccountsGrid" runat="server" AutoExpandColumn="description" Border="false" AutoScroll="true" NoLeafIcon="true">
                            <Columns>
                                <ext:TreeGridColumn Header="Decription" Width="150" DataIndex="description" />
                                <ext:TreeGridColumn Header="Account" Width="100" DataIndex="account" />
                                <ext:TreeGridColumn Header="Type" Width="150" DataIndex="assettype" />
                                <ext:TreeGridNumberColumn Header="Unrealized Gain/Loss" Width="125" DataIndex="totalgainloss" Align="Right" SortType="AsFloat">
                                    <XTemplate runat="server">
                                        <Html>
                                            {totalgainloss:usMoney}
                                        </Html>
                                    </XTemplate>
                                </ext:TreeGridNumberColumn>
                                <ext:TreeGridNumberColumn Header="Market Value" Width="125" DataIndex="marketvalue" Align="Right" SortType="AsFloat">
                                    <XTemplate ID="XTemplate1" runat="server">
                                        <Html>
                                            {marketvalue:usMoney}
                                        </Html>
                                    </XTemplate>
                                </ext:TreeGridNumberColumn>
                                <ext:TreeGridNumberColumn Header="Allocation %" Width="125" DataIndex="allocationpercent" Align="Right" SortType="AsFloat">
                                    <XTemplate runat="server">
                                        <Html>
                                            {allocationpercent} %
                                        </Html>
                                    </XTemplate>
                                </ext:TreeGridNumberColumn>
                            </Columns>
                        </ext:TreeGrid>
                    </Items>
                </ext:Panel>
            </Items>
        </ext:Panel>
    </Items>
</ext:FitLayout>