wpf - Dynamic Mvvm ContextMenu but SubMenu not showing -

the code snippet below works desired of couple posts here, no visual flaws more , incl. separator. tried add sub-contextmenu itemsource, , not working.

this have, said working expected, code snipped window 3 section 2 not (test submenu).

next xaml (isnullconverter1 converter test object not null).

<listbox itemssource="{binding stackvisualitems}" selecteditem="{binding selectedvisualitem}">      <listbox.itemtemplate>         <datatemplate datatype="models:visualitem">             <textblock text="{binding text2display}" />         </datatemplate>     </listbox.itemtemplate>      <listbox.contextmenu>         <contextmenu itemssource="{binding actioncollection}">              <contextmenu.resources>                 <controltemplate x:key="menuseparatortemplate">                     <separator />                 </controltemplate>                  <controltemplate x:key="dynamicmenutemplate">                     <contentpresenter content="{binding}">                         <contentpresenter.contenttemplate>                             <datatemplate datatype="wpf:contextmenuviewmodel">                                 <menuitem command="{binding actioncommand,                                                             targetnullvalue={x:null},                                                             fallbackvalue={x:null}}"                                           commandparameter="{binding actionparameter,                                                                      fallbackvalue={x:null},                                                                      targetnullvalue={x:null}}"                                           header="{binding displayname,                                                            targetnullvalue='targetnullvalue',                                                            fallbackvalue='fallbackvalue'}"                                           itemssource="{binding itemsources,                                                                 fallbackvalue={x:null},                                                                 targetnullvalue={x:null}}">                                     <menuitem.icon>                                         <image width="16"                                                height="16"                                                source="{binding path=icon,                                                                 fallbackvalue={x:null},                                                                 targetnullvalue={x:null}}" />                                     </menuitem.icon>                                 </menuitem>                             </datatemplate>                         </contentpresenter.contenttemplate>                     </contentpresenter>                 </controltemplate>             </contextmenu.resources>              <contextmenu.itemcontainerstyle>                 <style targettype="menuitem">                     <style.triggers>                         <datatrigger binding="{binding}" value="{x:null}">                             <setter property="template" value="{staticresource menuseparatortemplate}" />                         </datatrigger>                         <datatrigger binding="{binding path=., converter={staticresource isnullconverter1}}" value="false">                             <setter property="template" value="{staticresource dynamicmenutemplate}" />                         </datatrigger>                     </style.triggers>                 </style>             </contextmenu.itemcontainerstyle>          </contextmenu>     </listbox.contextmenu> </listbox> 

the contextmenuviewmodel looks this, trivial , nothing special:

public class contextmenuviewmodel : viewmodelbase {     private string _displayname;     private icommand _actioncommand;     private imagesource _icon;     private object _actionparameter;     private observablecollection<contextmenuviewmodel> _itemsources;      public contextmenuviewmodel(string displayname)     {         displayname = displayname;     }      public contextmenuviewmodel(string displayname, icommand contextmenuactioncommand)         : this(displayname)     {         actioncommand = contextmenuactioncommand;     }      public contextmenuviewmodel(string displayname, icommand contextmenuactioncommand, imagesource icon)         : this(displayname, contextmenuactioncommand)     {         icon = icon;     }      public string displayname     {         { return _displayname; }         set { _displayname = value; raisepropertychanged(() => displayname); }     }      public icommand actioncommand     {         { return _actioncommand; }         set { _actioncommand = value; raisepropertychanged(() => actioncommand); }     }      public imagesource icon     {         { return _icon; }         set { _icon = value; raisepropertychanged(() => icon); }     }      public object actionparameter     {         { return _actionparameter; }         set { _actionparameter = value; raisepropertychanged(() => actionparameter); }     }      public observablecollection<contextmenuviewmodel> itemsources     {         { return _itemsources; }         set { _itemsources = value; raisepropertychanged(() => itemsources); }     } } 

the dynamic contextmenu build way, incl. adding separator null value:

private void setupdynamiccontextmenu() {     imagesource copy = new bitmapimage(new uri(@"pack://application:,,,/resources/copy_16.png", urikind.absolute));     imagesource cut = new bitmapimage(new uri(@"pack://application:,,,/resources/cut_16.png", urikind.absolute));     imagesource delete = new bitmapimage(new uri(@"pack://application:,,,/resources/delete_16.png", urikind.absolute));     actioncollection = new observablecollection<contextmenuviewmodel>();     actioncollection.add(new contextmenuviewmodel("copy all", new relaycommand<string>(copyallcommand, o => cancopyall()), copy));      //does not work: submenu     actioncollection.add(new contextmenuviewmodel("test submenu"));     actioncollection[actioncollection.count - 1].itemsources = new observablecollection<contextmenuviewmodel>();     actioncollection[actioncollection.count - 1].itemsources.add(new contextmenuviewmodel("copy test", new relaycommand<string>(copyallcommand, o => true), cut));      actioncollection.add(null); //separator     actioncollection.add(new contextmenuviewmodel("copy current", new relaycommand<string>(copycurrentcommand, o => true), cut));     //actioncollection.add(new contextmenuviewmodel("copy selection", new relaycommand<string>(copyselectioncommand, o => true))); }