This will apply changes such as the `PreferredBackBufferWidth/Height` before the user actually runs `ApplyChanges()` in the game. It's probably very subtle for most games, but if someone adds, for instance, Alt-Enter ToggleFullscreen to their game, it may use settings that were not yet confirmed by the player. (Similar note: I just noticed VSync changes are never used anywhere... would this explain the VSync #ifdef-ery we've got going on in `SynchronizeWithVerticalRetrace`?)

Does the replacement code below still work for your stuff? I think it's more "correct", but forced-fullscreen platforms might break, dunno:

    if (IsFullscreen)
    {
        _game.Platform.EnterFullScreen();
    }
    else
    {
        _game.Platform.ExitFullScreen();
    }