public void Render(GameTime gameTime)
{
if (_activeScreen == null || !_activeScreen.CanRender) return;
var startTime = gameTime.TotalElapsedTime;
if (!this.FpsLock || gameTime.TotalElapsedTime >= _nextRenderTime)
_activeScreen.Render(gameTime);
FrameTime = gameTime.TotalElapsedTime - startTime;
_nextRenderTime = gameTime.TotalElapsedTime + ((1000 / Constants.MAX_FPS) - this.FrameTime);
}