How do i set the size of the tooltip dialog box. the tooltip text must be displayed in one line rather than wrapping the text to other line.

in firefox tooltip text is showed in one line but in IE the tooltip text is wrapped . i.e text is displayed in 2 lines.

asp:Image runat="server" ID="iUrl" Visible="false" ImageUrl="~/Widgets/FMP_Printers/images/status icons/icon_Fault_Enabled.gif" />

  if (txtUrl.Text.ToUpper().IndexOf("HTTP://") < 0 && txtUrl.Text.ToUpper().IndexOf("HTTPS://") < 0)
    {
        iUrl.Visible = true;

        iUrl.ToolTip = "ghghghghghghghghghghghghghghghghghghghghghghghghghghghghghghghgh";
        valid = false;
    }