c# - Background worker does not work properly in do work event in wpf -

i have read post did not me :

background worker not work in wpf

i using background worker in wpf(c#) , want when reading text file , shows "loading ...." not show. code :

    private delegate void upmdlg();     private delegate void upmdlg2();      private void callmetoread()     {         streamreader str = new streamreader("c:\\test.txt");         while (!str.endofstream)         {             richtextbox1.appendtext(str.readtoend());         }     }      private void callmetochangelabel()     {         label1.foreground = brushes.red;         label1.content = "loading ....";     }      private void window_loaded(object sender, routedeventargs e)     {         label1.foreground = brushes.yellow;         label1.content = "idle";          backgroundworker bg = new backgroundworker();          bg.dowork += delegate(object s, doworkeventargs args)         {             upmdlg mo = new upmdlg(callmetochangelabel);             label1.dispatcher.begininvoke(mo, dispatcherpriority.normal);              upmdlg mo2 = new upmdlg(callmetoread);             richtextbox1.dispatcher.begininvoke(mo2, dispatcherpriority.normal);          };         bg.runworkercompleted += delegate(object s, runworkercompletedeventargs arg)         {             label1.foreground = brushes.green;             label1.content = "done ....";         };          bg.runworkerasync();     } 

thanks help.

try synchronizationcontext.current post execution ui code. works me well:

    private void window_loaded(object sender, routedeventargs e)     {         label1.foreground = brushes.yellow;         label1.content = "idle";          var context = synchronizationcontext.current;          backgroundworker bg = new backgroundworker();          bg.dowork += (o, args) =>          {              context.post(state => callmetochangelabel(),null);             context.post(state => callmetoread(), null);         };         bg.runworkercompleted += (o, args) =>          {             label1.foreground = brushes.green;             label1.content = "done ....";         };          bg.runworkerasync();     } 

btw: posts describes how synchronizationcontext works: it's synchronizationcontext , understanding synchronizationcontext