I've added a new TabFx plugin which fires a visual effect when a Tab becomes Active or is selected. The default fx is "frame" and shows a ripple of exploding attenuating borders around the Tab.

Example

<ext:TabPanel ID="TabPanel1" runat="server" ActiveTabIndex="0" Height="185" Width="300">
    <Tabs>
        <ext:Tab ID="Tab1" runat="server" Title="Tab 1" />
        <ext:Tab ID="Tab2" runat="server" Title="Tab 2" />
        <ext:Tab ID="Tab3" runat="server" Title="Tab 3" />
    </Tabs>
    <Plugins>
        <ext:TabFx runat="server" />
    </Plugins>
</ext:TabPanel>
Hope this helps.