fix(render): disable browser scroll anchoring on the table holder

src/scss/tabulator.scss

@@ -440,6 +440,7 @@ $rangeHeaderTextHighlightBackground: #000000 !default; //header text color when
 		width:100%;
 		white-space: nowrap;
 		overflow:auto;
+		overflow-anchor: none;
 		-webkit-overflow-scrolling: touch;
 
 		&:focus{

test/e2e/overflow-anchor.spec.ts

@@ -0,0 +1,21 @@
+import { test, expect } from "@playwright/test";
+import { join } from "path";
+
+// Regression coverage for disabling browser scroll anchoring on the table
+// holder. The virtual renderer manages scrollTop/padding itself; Chrome's
+// scroll anchoring double-compensates when rows are inserted above the
+// viewport, causing drift on scroll-up. The fix sets overflow-anchor:none on
+// .tabulator-tableholder. This guards that the rule survives in the built CSS
+// and is applied by the browser.
+test.describe("table holder disables browser scroll anchoring", () => {
+	test("computed overflow-anchor is none", async ({ page }) => {
+		await page.goto(`file://${join(__dirname, "scroll-jump.html")}`);
+		await page.waitForSelector(".tabulator-tableholder");
+
+		const value = await page
+			.locator(".tabulator-tableholder")
+			.evaluate((el) => getComputedStyle(el).overflowAnchor);
+
+		expect(value).toBe("none");
+	});
+});

test/e2e/scroll-jump.spec.ts

@@ -21,12 +21,16 @@ import { join } from "path";
 // HOW THE JUMP IS MEASURED
 // When you scroll up by D pixels the visible content must move DOWN by exactly
 // D. We track one identifiable row element across a scroll-up step and compare
-// how far it moved on screen ("moved") with how far the holder actually
-// scrolled ("scrolled"). For a correct virtual DOM the row is glued to the
-// content so moved === scrolled; "jump = moved - scrolled" is therefore the
-// number of pixels the content shifted underneath the scroll position. This
-// metric is independent of whether scrollTop itself is trustworthy (it isn't,
-// once the bug fires).
+// how far it moved on screen ("moved") with the D we asked for, so
+// "jump = moved - requested" is the number of pixels the content shifted that
+// the user did not ask for.
+//
+// We deliberately do NOT compare against the holder's own scrollTop delta.
+// A virtual renderer revises its total scrollHeight as it measures real row
+// heights, and scrollTop is measured from the top of that changing document, so
+// it shifts by the height correction while nothing on screen moves at all. That
+// makes "moved - scrolled" report a jump for a view that is perfectly steady.
+// The requested delta has no such term.
 //
 // The companion "gentle scrolling" test below demonstrates that this metric
 // reads ~0 for well-behaved scrolling, so a large reading is a real jump.
@@ -133,7 +137,7 @@ async function scrollUpAndMeasure(
 				id: beforeScrolling.id,
 				moved: Math.round(moved),
 				scrolled: Math.round(scrolled),
-				jump: Math.round(moved - scrolled),
+				jump: Math.round(moved - delta),
 			});
 		}
 	}
@@ -169,9 +173,8 @@ test.describe("Vertical scroll jumping with variable height rows (#3654)", () =>
 		// Sanity: the scroll-up actually moved content.
 		expect(jumps.length).toBeGreaterThan(0);
 
-		// The tracked row should stay glued to the content (move by exactly the
-		// scroll distance, give or take sub-pixel rounding). A larger reading
-		// is the #3654 jump.
+		// The tracked row should move by exactly the distance we scrolled up,
+		// give or take sub-pixel rounding. A larger reading is the #3654 jump.
 		expect(worstJump).toBeLessThanOrEqual(20);
 	});
 
@@ -218,9 +221,12 @@ test.describe("Vertical scroll jumping with grouped variable height rows (#3654)
 		await page.waitForTimeout(50);
 
 		// Track data rows only, never the group header rows.
+		// The step must stay well under the ~275px viewport: a step that turns
+		// over the whole rendered window leaves no row present both before and
+		// after the scroll, so nothing can be measured.
 		const jumps = await scrollUpAndMeasure(
 			page,
-			250,
+			80,
 			40,
 			".tabulator-row:not(.tabulator-group)",
 		);