How to change tab index from the child page

[vjvjvjvj]

Hi, I have a tab container with two tab panels on default.aspx as

Default.aspx

<ajaxToolkit:ToolkitScriptManager ID="ScriptManager1" runat="server" />

    <ajaxToolkit:TabContainer   ID="LayerTabContainer" 
                                runat="server" 
                                ActiveTabIndex="0" 
                                Height="600px">
        <ajaxToolkit:TabPanel   ID="CreateLayerPanel" 
                                runat="server">
            <HeaderTemplate >
            Layer configuration
            </HeaderTemplate>
            <ContentTemplate>
           
                <iframe id="LayerConfig" 
                        style="WIDTH: 100%; HEIGHT: 100%" 
                        src="Layers.aspx" 
                        frameborder="0" 
                        scrolling="yes">
				</iframe>
            
            </ContentTemplate>
        </ajaxToolkit:TabPanel>
       <ajaxToolkit:TabPanel   ID="PreviewMapPanel" 
                                runat="server">
            <HeaderTemplate >
            Preview Map
            </HeaderTemplate>
            <ContentTemplate>
           
                <iframe id="Iframe1" 
                        style="WIDTH: 100%; HEIGHT: 100%" 
                        src="Preview.aspx" 
                        frameborder="0" 
                        scrolling="yes">
				</iframe>
            
            </ContentTemplate>
        </ajaxToolkit:TabPanel>
    </ajaxToolkit:TabContainer>

The first tab panel hosts Layers.aspx and layer.aspx has a Button. When I click this button from Layer.aspx, I want the active tab (on default.aspx) to change to second tab panel which hosts preview.aspx. I can not get hold of the tabcontainer in the button click event in the child page. Any tips how to achieve this? Thanks, Vijay