<!DOCTYPE html>
<html>
<head>
<script runat="server">
Sub ChangeBorderStyle(obj As Object, e As EventArgs)
button1.BorderStyle = CType([Enum].Parse(GetType(BorderStyle),"Solid"), BorderStyle)
End Sub
</script>
</head>
<body>
<form runat="server">
<asp:Button id="button1" runat="server" BorderStyle="Dotted" BorderWidth="10px" Text="Change" BorderColor="#FF0000" OnClick="ChangeBorderStyle" />
</form>
</body>
</html>