c# - Keep focus on main window while doing lengthy operations -

i have wpf application calls dll when user clicks on button. dll lengthy operations , while that, cannot interact mainwindow, e.g scroll down datagrid logging update messages, switch tabs etc. how can keep mainwindow activated while dll running ? thought backgroundworker calls .activate() method whenever window.deactivated occurs, wouldn't terribly resource-consuming , slow down other dll takes lot of time ?

i'm waiting suggestions :) thank you

it seems running lengthy operation in ui thread. try running in separate thread.

    private void button_click(object sender, routedeventargs e)     {         task.factory.startnew(calllengthydllmethod);     }      private void calllengthydllmethod()     {         thread.sleep(10000); // simulating lengthy operations         messagebox.show("done!");     }