c# - using the FileSystemWatcher to dynamically alter the items in a combo box -

ok, trying use filesystemwatcher watch changes in directory , dynamically change items in combo box. populatecb() method works when user control loaded. , added break point inside watcher changed event breaks when change contents of directory. know events being triggered , watcher_changed method being called. contents of combo-box not change... doing wrong?

public partial class htmlviewer : usercontrol {     private list<string> emails = new list<string>();     filesystemwatcher watcher = new filesystemwatcher("emailtemplates", "*.msg");     public htmlviewer()     {         initializecomponent();         populatecb();         watcher.changed += watcher_changed;         watcher.created += watcher_changed;         watcher.deleted += watcher_changed;         watcher.renamed += watcher_changed;         watcher.enableraisingevents = true;      }      void watcher_changed(object sender, filesystemeventargs e)     {         this.dispatcher.invoke((action)(() =>             {                 populatecb();             }             ));      }     private void populatecb()     {         emails.clear();         foreach(var file in directory.enumeratefiles("emailtemplates", "*.msg", searchoption.alldirectories))         {             emails.add(file);         }         emailselector.itemssource = emails;     } } 

the simplest solution set itemsource null before changing list<string> emails

private void populatecb() {     emailselector.itemssource = null;     emails.clear();     foreach(var file in directory.enumeratefiles("emailtemplates", "*.msg", searchoption.alldirectories))     {         emails.add(file);     }     emailselector.itemssource = emails; } 

without not changing previous itemsource. same object. list<string> has no capability notify binding infrastructure of wpf of changes elements. clearing items, readding them totally invisible combobox. instead setting itemsource = null, , resetting again informs combobox of changes.

a possible (and better option) change list observablecollection has capability notifiy changes