I answer to myself specifying the problem. What I'm trying to achieve is something similar to the picture:

The code in the xml is this:

 <Object>
  <Token>[SOLPARTMENU:2]</Token>
  <Settings>
   <Setting>
    <Name>display</Name>
    <Value>vertical</Value>    
   </Setting>
   <Setting>
    <Name>menucontainercssclass</Name>
    <Value>QM_MenuContainer</Value>    
   </Setting>
   <Setting>
    <Name>menuitemcssclass</Name>
    <Value>QM_MenuItem</Value>    
   </Setting>   
   <Setting>
    <Name>menuitemselcssclass</Name>
    <Value>QM_MenuItemSel</Value>    
   </Setting>   
   <Setting>
    <Name>menubreakcssclass</Name>
    <Value>QM_MenuBreak</Value>    
   </Setting>   
   <Setting>
    <Name>submenucssclass</Name>
    <Value>QM_Submenu</Value>    
   </Setting>   
   <Setting>
    <Name>userootbreadcrumbarrow</Name>
    <Value>false</Value>    
   </Setting>
   <Setting>
    <Name>usearrows</Name>
    <Value>false</Value>    
   </Setting>   
   <Setting>
    <Name>rootmenuitembreadcrumbcssclass</Name>
    <Value>QM_rootmenuitembreadcrumb</Value>    
   </Setting>   
   <Setting>
    <Name>submenuitembreadcrumbcssclass</Name>
    <Value>QM_submenuitembreadcrumb</Value>    
   </Setting>
   <Setting>
    <Name>rootmenuitemcssclass</Name>
    <Value>QM_rootmenuitem</Value>    
   </Setting>   
   <Setting>
    <Name>rootmenuitemactivecssclass</Name>
    <Value>QM_rootmenuitemactive</Value>    
   </Setting>   
   <Setting>
    <Name>submenuitemactivecssclass</Name>
    <Value>QM_submenuitemactive</Value>    
   </Setting>
   <Setting>
    <Name>rootmenuitemselectedcssclass</Name>
    <Value>QM_rootmenuitemselected</Value>    
   </Setting>   
   <Setting>
    <Name>submenuitemselectedcssclass</Name>
    <Value>QM_submenuitemselected</Value>    
   </Setting>   
   <Setting>
    <Name>rootmenuitemrighthtml</Name>
    <Value><div class="sep"></div></Value>    
   </Setting>      
   <Setting>
    <Name>cleardefaults</Name>
    <Value>true</Value>    
   </Setting>       
  </Settings>
 </Object>

then I define these css in the stylesheet editor:

.QM_MenuItem {
background-color:#ff0000;
border:1px #000000 solid;
margin-bottom:7px;
}

Margin-bottom and border are ignored. I dont know how to render a border of the rootmenuitems and how to have space beetween them. The property "rootmenuitemrighthtml" seems not to render anything of what I set as value. Any idea?

thanks for help