c# 4.0 - How do you break a while loop with a keypress in WPF? -

i've seen answers question of how break out of while loop keypress console app , winforms app not wpf app. so, uh, how do it? thanks.

okay, let's elaborate: doesn't work in wpf (non-console) app. throws runtime error:

while(!console.keyavailable) { //do work }     

mainwindow.xaml:

<window x:class="wpfapplication34.mainwindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         title="mainwindow"         width="525"         height="350">   <grid>     <textblock x:name="tb" />   </grid> </window> 

mainwindow.xaml.cs:

public partial class mainwindow:window {   private int _someval = 0;   private readonly cancellationtokensource cts = new cancellationtokensource();    public mainwindow() {     initializecomponent();     loaded += onloaded;   }    private async void onloaded(object sender, routedeventargs routedeventargs) {     keydown += onkeydown;     while (!cts.iscancellationrequested) {       await task.delay(1000); // long task       tb.text = (++_someval).tostring();     }   }    private void onkeydown(object sender, keyeventargs keyeventargs) {     if (keyeventargs.key == key.a)       cts.cancel();   } } 

it's rough demo, take concept. thing specific wpf here manner of capturing key-press. else relating breaking while loop same across console app or wpf or winforms.