Problem Prevent cotp/Past in Opera

Question

hi frnds,,

prevent past in text box not working , cont prevent past in opera only other browsers it ll cork fine,

my code is
<asp:TextBox ID="txtpassword" TabIndex="2" Width="142px" oncopy="return false;" onpaste="return false;"
                                                                                            oncut="return false;" oninput="return false;" TextMode="Password" ToolTip="Enter Password" runat="server"></asp:TextBox>