c# - Async/Await with a WinForms ProgressBar -

i've gotten type of thing working in past backgroundworker, want use new async/await approach of .net 4.5. may barking wrong tree. please advise.

goal: create component long-running work , show modal form progress bar it's doing work. component handle window block interaction while it's executing long-running work.

status: see code below. thought doing until tried interacting windows. if leave things alone (i.e. don't touch!), runs "perfectly", if click on either window program hangs after long-running work ends. actual interactions (dragging) ignored though ui thread blocked.

questions: can code fixed easily? if so, how? or, should using different approach (e.g. backgroundworker)?

code (form1 standard form progressbar , public method, updateprogress, sets progressbar's value):

using system; using system.diagnostics; using system.threading; using system.threading.tasks; using system.windows.forms;  namespace consoleapplication1 { class program {     static void main(string[] args)     {         console.writeline("starting..");         var mgr = new manager();         mgr.goasync();         console.writeline("..ended");         console.readkey();     } }  class manager {     private static form1 _progressform;      public async void goasync()     {         var owner = new win32window(process.getcurrentprocess().mainwindowhandle);         _progressform = new form1();         _progressform.show(owner);          await go();          _progressform.hide();     }      private async task<bool> go()     {         var job = new longjob();         job.onprogress += job_onprogress;         job.spin();         return true;     }      void job_onprogress(int percent)     {         _progressform.updateprogress(percent);     } }  class longjob {     public event progressed onprogress;     public delegate void progressed(int percent);      public void spin()     {         (var = 1; <= 100; i++)         {             thread.sleep(25);             if (onprogress != null)             {                 onprogress(i);             }         }     } }  class win32window : iwin32window {     private readonly intptr _hwnd;     public win32window(intptr handle)     {         _hwnd = handle;     }     public intptr handle     {                 {             return _hwnd;         }     } } } 

@stephencleary's answer correct. though, had make little modification answer behavior think op wants.

public void goasync() //no longer async blocks on appication.run {     var owner = new win32window(process.getcurrentprocess().mainwindowhandle);     _progressform = new form1();      var progress = new progress<int>(value => _progressform.updateprogress(value));      _progressform.activated += async (sender, args) =>         {             await go(progress);             _progressform.close();         };      application.run(_progressform); }