From 73cae6198f23f5d09b2550845d2ca36b3c579e44 Mon Sep 17 00:00:00 2001
From: Andrew Kingston <andrew@kingston.dev>
Date: Thu, 15 Jun 2023 14:23:33 +0100
Subject: [PATCH] Improve grid logic around vertically inverting row popovers

---
 .../frontend-core/src/components/grid/stores/viewport.js   | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/packages/frontend-core/src/components/grid/stores/viewport.js b/packages/frontend-core/src/components/grid/stores/viewport.js
index bda56dc34f..f258b7daef 100644
--- a/packages/frontend-core/src/components/grid/stores/viewport.js
+++ b/packages/frontend-core/src/components/grid/stores/viewport.js
@@ -110,9 +110,10 @@ export const deriveStores = context => {
   const rowVerticalInversionIndex = derived(
     [visualRowCapacity, rowHeight],
     ([$visualRowCapacity, $rowHeight]) => {
-      return (
-        $visualRowCapacity - Math.ceil(MaxCellRenderHeight / $rowHeight) - 2
-      )
+      const maxCellRenderRows = Math.ceil(MaxCellRenderHeight / $rowHeight)
+      const topIdx = $visualRowCapacity - maxCellRenderRows - 2
+      const bottomIdx = maxCellRenderRows + 1
+      return Math.max(topIdx, bottomIdx)
     }
   )