c# - How to disable ItemsSource synchronization with Text property of ComboBox -

i use combobox binding string property of view model. choose combobox instead of textbox, because want have option choose list (as suggestion), don't want change selected text if itemssource changes.

i tried set issynchronizedwithcurrentitem property false, when list of suggestions change (at position of selected text), text changes empty. seems combobox has remembered entered text in list , when item disappears, text property cleared.

so question is: bug, or doing wrong? if bug, suggest work around?

i created sample project preproduces this:

in xaml:

<window x:class="testproject1.mainwindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         title="mainwindow" height="350" width="525">     <grid>         <combobox issynchronizedwithcurrentitem="false" itemssource="{binding items}"                   iseditable="true" text="{binding selectedtext, updatesourcetrigger=propertychanged}"                   horizontalalignment="left" margin="10,39,0,0" verticalalignment="top" width="120"/>         <button click="button_click" content="update list"                  horizontalalignment="left" margin="10,82,0,0" verticalalignment="top" width="75"/>     </grid> </window> 

in code behind:

public partial class mainwindow : window, inotifypropertychanged     {         public mainwindow() {             initializecomponent();              this.datacontext = this;             items = new list<string>() { "0", "1", "2" };         }          public event propertychangedeventhandler propertychanged;         private void raisepropertychanged(string propertyname) {             if (propertychanged != null) {                 propertychanged(this, new propertychangedeventargs(propertyname));             }         }          private list<string> _items;         public list<string> items {// use ienumerable<string> linq, effect same             { return _items; }             set {                 if (_items != value) {                     _items = value;                     raisepropertychanged("items");                 }             }         }          private string _selectedtext;         public string selectedtext {             { return _selectedtext; }             set {                 if (_selectedtext != value) {                     _selectedtext = value;                     raisepropertychanged("selectedtext");                 }             }         }          private void button_click(object sender, routedeventargs e) {             var changed = items.tolist();//clone             int index = changed.indexof(selectedtext);             if (index >= 0) {                 changed[index] += "a";//just change selected value             }             items = changed;//update new list         }      } 

after itemssource has changed, raise property changed on selected text refresh ui.

so in items collection setter, make change:

raisepropertychanged("items"); raisepropertychanged("selectedtext"); 

edit: in example aren't changing itemsource, changing text of item selected 1 having text binding on old text. expecting see/happen? wanting selected item stay same, if text changes?