Conditional Display of Download Button in ASP.NET GridView TemplateField

<asp:TemplateField HeaderText="Download Document">
    <ItemTemplate>
        <asp:ImageButton ID="btnDownload" runat="server"
         CommandName="Download"
         CommandArgument='<%# Eval("Document_ID") & "," & Eval("Document_Name") %>'
         ImageUrl="download.png"
         ToolTip='<%#"Download " & Eval("Document_Name") %>'
         Visible='<%# Not(Eval("Document_ID") = -1) %>' />
    </ItemTemplate>
</asp:TemplateField>

JavaScript to determine if clicked element has target

function targetExists(e)
{
    var retVal = true;
    var event = e || window.event;
    if (!event.target)
    {
        event.target = event.srcElement;
    }
    if (event.target == undefined || event.target == "")
    {
        retVal = false;
    }
    return retVal;
}

Adapted from http://snipplr.com/view/2565/which-element-was-clicked (original source was http://quirksmode.org).

Rounded Corners Generator

Web site that creates rounded corners for you  http://jalenack.com/roundedstage thanks to Andrew Sutherland.

Tabs Generator

Web site that creates tab graphics for you  http://www.tabsgenerator.com thanks to Alex La Rosa and Fabio Fidanza.