Quick, make a dialog appear…

<script type="text/javascript" src="http://www.schimsky.com/jquery/jquery-3.4.1.min.js"></script>

<script type="text/javascript" src="http://www.schimsky.com/jquery/jquery-ui-1.12.1.custom/jquery-ui.min.js"></script>

<link type="text/css" rel="Stylesheet" href="http://www.schimsky.com/jquery/jquery-ui-1.12.1.custom/jquery-ui.min.css"/>

<div id='dvEditor' style="display: none;"> Hellow World!  I'm a modal dialog :-) </div>

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click

Dim s As String

        s = "<script> $('#dvEditor').dialog({show: {effect:'slide', direction:'right'},hide: {effect:'slide', direction:'left'}, height: 300, width: 400,modal:true });  </script>"

Page.ClientScript.RegisterStartupScript(Me.GetType(), "June21Key", s)

End Sub