gistfile1.cs

                    var i = 0;
                    var upperBound = itemsToDisplay + startOffset;
                    foreach (var item in Items)
                    {
                        if (i < startOffset || i >= upperBound)
                        {
                            if (item.IsDisplayed)
                            {
                                _layout.Remove(item.ProxyDrawable);
                                item.IsDisplayed = false;
                            }
                            i++;
                            continue;
                        }
                        i++;

                        if (!item.IsDisplayed)
                        {
                            _layout.Add(item.ProxyDrawable, col * (Size.Width / ItemsPerLine), row * ((Size.Width / ItemsPerLine) + 20));
                            item.IsDisplayed = true;
                            item.Size = new Size((int)itemWidth, (int)itemHeight);
                        }
                        else
                        {
                            _layout.Move(item.ProxyDrawable, col * (Size.Width / ItemsPerLine),
                                     row * ((Size.Width / ItemsPerLine) + 20));
                            item.Size = new Size((int)itemWidth, (int)itemHeight);
                        }

                        col++;
                        if (col == ItemsPerLine)
                        {
                            row++;
                            col = 0;
                        }
                    }