Right-scrolling makes the text bounce back

When a buffer is horizontally scrolled to the right with the trackpad, as soon as the end of the line is reached the text bounces back to the left. If one keeps scrolling, the text bounces back repeatedly. Would it be possible to make it more stable, i.e., when the far right is reached, the text should not move?

I attach a screenshot to illustrate the issue.

复现 issue 中描述的触控板行为，并使用附带的屏幕截图作为回弹效果的参考。跟踪 MacVim 对水平滚动的处理，找出为什么到达最右侧后文本又会向左移动。完成的标准是继续向右滚动时 buffer 能稳定停留在行尾，不再反复回弹。