Yes, you are right, as long as no horizontal scrolling is required what you suggest can indeed work. And this has an extra benefit when a file has some extra header lines before the column headers. It keeps the complete upper portion of the columnar file stationary and visible and allows one to scroll vertically and bring just the column headings into view.
But sadly enough, “LifeTime” is right too! There is probably no possibility to lock the side-scrolling for the two split windows.
So Yutaka, I would strongly suggest that your implementation of such a feature will:
1) take into account an arbitrary number of extra header lines, and
2) enable horizontal scrolling,
otherwise its usefulness will be rather limited.