I got a WPF application that shows a button bound to a command like that:

<Button Command="{Binding Path=TestrunStartCommand}" Content="GO!">

The command is defined like that:

public ICommand TestrunStartCommand
{
    get { return new RelayCommand(TestrunStartExecute, () => !IsTestrunInProgress); }
}

public bool IsTestrunInProgress
{
    get{
        return _isTestrunInProgress;
    }
    set{
        _isTestrunInProgress = value;
        RaisePropertyChanged(IsTestrunInProgressPropertyName);
    }
}

The problem is, the button won't be enabled immediately after I set IsTestrunInProgress to false, but only after I click inside the application window.

Could you help me understand this behaviour and show me how to fix this?

Further reading: wpf command pattern - when does it query canexecute

c# wpf mvvm-light
Edit
Report