ASP.NET: Freeze/Lock Web Page While Loading

When processing a request, web page will be freezed/locked. Hence, users are unable to click any button and just wait.

The following CSS enable Div height 100%:

ASP.NET

C#

protected void submitButton_Click(object sender, EventArgs e)
{
    System.Threading.Thread.Sleep(10000); //loading
}

Last but not least, these code works fine for IE6, Chrome and Firefox.

References:
CSS Div Height 100%
How to Freeze Webpage while it is being processed in .Net 2.0 using AJAX?
Lock/Freeze Web Page using jQuery