public App()
{
w = new MyWindow();
//You also can pass Action to open new window of some sort here
//or other things, that VM can't have access to
vm = new MyViewModel(true);
w.DataContext = vm;
w.Show();
}
private void OpenDialog_Clicked(object sender, EventArgs eventArgs)
{
var dialog = new MyWindow(this);
dialog.Show();
}