Cfmenuitem to open a popup window

I am trying to open a popup window with cfmenuitem, it works but give me a javascirpt error that I am not sure how to fix. Here is what I am doing:

<cfmenu name="myMenu" type="horizontal"  childstyle="position:relative; z-index: 3000000; "
                             fontsize="10"  font="Verdana, Arial, Helvetica, sans-serif"  bgcolor="#f#f9f40;"
                            selecteditemcolor="##dd6b04" selectedfontcolor="##FFFFFF" menustyle="border: 1;">

                        <cfmenuitem
                            href="http://yahoo.com" display="Yahoo" target="New"/>
                        <cfmenuitem
                            href="http://google.com" display="google" target="New"/>

                        <cfmenuitem name="popup" href="javascript:window.open('pop.cfm','mywin','width=300,height=200,left=400,top=400,screenX=0,screenY=100'); index.cfm;" display="Popup"/>

</cfmenu>

The current file name is index.cfm. I want the page stay in index.cfm while displaying pop.cfm on the top. It is working fine with everything except a javascript error indicating "index" is undefiined. But if I remove "index.cfm" from the tag, I will get a blank page. Is there anything to fix this?

All I want to stay in the same page when clicking the menu item with the pop window on top focused.

Please help.

Thanks