Challange: Dynamic Freeze Panes based on what is visible

Hello there,

this one does not fall in the "absolutely necessary for my job" but is rather a challange which would be cool to make.

The idea is that there's a huge table in which there are some rows which are "summary" and others which are "information" of the summary row above them, something like

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I wolud like that as the user scrolls down, Summary A is frozen as long as the first row visible underneath is still some "A info" row, once the Summary B row is about to disappear underneath Summary A (as the user scrolls down), Summary B should be the frozen row (I guess it would be necessary to hide all rows between it and the title row) and so on. Of course it should also work in referse: If the row visible underneath Summary B is B info 1 and the user continues to scroll up, the interface should change to freeze summary A underneath the title in a smooth way

This is more or less how the photo management software Picassa works when showing thumbnails of pictures in folders.


anyone up to the challange?

I've checked around and for scroll events, but they only provide the top left cell, I wonder how that works with frozen panes. Othe than that, since I work in a closed environment, it's not really possible to intall add-ins and stuff like this (even DLLs, but I'm not sure)

once I write here I keep thinking about it...

I managed the effect I wished, albeit with the event selection change, that means the user needs to be selecting rows outside the main view to force the scroll which causes the heading to change. It does not work with mousewheel alone.

I read this article about detecting scroll, but in the environment I'm in it's not possible to make it work, and would probably fail in other machines. Oh well.

I tried to make the sheet scroll when user pushes down arrow, but apparently key detection does not work on worksheet... and could not find a way to know if the selection was moving down or up and scroll the sheet programatically

anyway. I publish the workbook if anyone is interested