wpf combobox binding is empty -

i trying work out wpf difficulties. combobox seems basic issue can't have populated after reading possible similar post.

the difficulty think combobox defined in resource, here resource code:

<resourcedictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"                 xmlns:s="clr-namespace:diagramdesigner">  <resourcedictionary.mergeddictionaries>     <resourcedictionary source="styles/shared.xaml"/>     <resourcedictionary source="styles/toolbar.xaml"/> </resourcedictionary.mergeddictionaries>  <toolbar x:key="mytoolbar" height="120">      <!--languages-->     <groupbox header="localization" style="{staticresource toolbargroup}" margin="3">         <grid>             <combobox height="23" horizontalalignment="center"                        verticalalignment="top"  width="120"                       itemssource="{binding _langliststring}"                          displaymemberpath="valuestring"                          selectedvaluepath="valuestring"                          selectedvalue="{binding langstring}"                       />         </grid>     </groupbox>    </toolbar> 

my data object defined follow:

public partial class window1 : window {      list<comboboxitemstring> _langliststring = new list<comboboxitemstring>();      // object bind combobox selections to.     private viewmodelstring _viewmodelstring = new viewmodelstring();       public window1()     {         // localization settings         _langliststring.add(new comboboxitemstring()); _langliststring[0].valuestring = "en-gb";         _langliststring.add(new comboboxitemstring()); _langliststring[1].valuestring = "fr-fr";         _langliststring.add(new comboboxitemstring()); _langliststring[2].valuestring = "en-us";           // set data context window.         datacontext = _viewmodelstring;           initializecomponent();       } 

and modelview:

/// class provides object fill combobox /// can bound string fields in binding object. public class comboboxitemstring {     public string valuestring { get; set; } }   //______________________________________________________________________ //______________________________________________________________________ //______________________________________________________________________    /// class used bind combobox selections to. must implement  /// inotifypropertychanged in order data binding  /// work correctly. public class viewmodelstring : inotifypropertychanged {     /// need void constructor in order use object element      /// in xaml.     public viewmodelstring()     {     }      private string _langstring = "en-gb";      /// string property used in binding examples.     public string langstring     {         { return _langstring; }         set         {             if (_langstring != value)             {                 _langstring = value;                 notifypropertychanged("langstring");             }         }     }      #region inotifypropertychanged members      /// need implement interface in order data binding     /// work properly.     private void notifypropertychanged(string propertyname)     {         if (propertychanged != null)         {             propertychanged(this, new propertychangedeventargs(propertyname));         }     }      public event propertychangedeventhandler propertychanged;      #endregion } 

i don't know try else. has idea of going on, , why combobox stays empty?

many thanks.

you can bind public properties

 itemssource="{binding _langliststring}" 

can not work because _langliststring not public property