Adding separator on top level service menu

Question

I have a top level service menu, now I want to add a separator before this menu,

Here's my current service menu header:

[Desktop Entry]
Type=Service
Actions=A;_SEPARATOR_;B;C;
X-KDE-Priority=TopLevel
X-KDE-Submenu=Debuggers
ServiceTypes=KonqPopupMenu/Plugin,all/allfiles
Encoding=UTF-8
MimeType=application/x-ms-dos-executable;application/x-executable;application/x-msdownload;

Now I would have a sub menu named Debuggers, and it's like this,

Debuggers -->  A
             -----
               B
               C

What I want is like this,

---------
Debuggers -->  A
             -----
               B
               C

So, how should I add the separator for the top level menu?