restore vertical axes of scroll bars

README.md

@@ -40,14 +40,18 @@ have comments keep showing the count as before.
 When you drop a card (or Kanboard auto-refreshes the board via polling), it rebuilds the
 board with `$("#board-container").replaceWith(...)`, and the new element starts scrolled to
 the far left -- so the view jumps back to the first column. A **full page reload** (for
-example clicking the Done/Todo badge, which navigates and redirects back to the board) does
-the same. This tweak remembers the horizontal scroll position and restores it in both cases,
-so the board stays where you were.
+example clicking the Todo/Done badge or the "Mark all" action, which navigate and redirect back to
+the board) does the same. This tweak remembers the scroll position -- **horizontal and vertical** --
+and restores it in both cases, so the board stays where you were.
 
-- Implemented in `Asset/js/keep-scroll.js`: it observes the stable parent (the container
-  itself is replaced) and restores `scrollLeft` on whichever `#board-container` is current
-  after an AJAX rebuild, and persists the position per board in `sessionStorage` so it also
-  survives a full page reload.
+- Implemented in `Asset/js/keep-scroll.js`: it observes the stable parent (the container itself is
+  replaced) and restores, on whichever `#board-container` is current after an AJAX rebuild and again
+  after a full reload (persisted per board in `sessionStorage`):
+  - the **horizontal** position (`#board-container.scrollLeft`);
+  - the **page vertical** position in expanded mode (`window.scrollY`);
+  - the **per-column vertical** position in compact/collapsed mode -- each native
+    `.board-task-list-compact` list, keyed by its `data-swimlane-id` + `data-column-id`, so every
+    column keeps its own place independently (works with or without ShrinkVertically).
 - **On by default.** Toggle it under "Settings -> Organon Tweaks".
 
 ### Open a card only on a quick click