From b19fd0dabfadf6689abaad84451647268a8d74a4 Mon Sep 17 00:00:00 2001
From: tophf <tophf@gmx.com>
Date: Fri, 13 Nov 2020 19:04:06 +0300
Subject: [PATCH] prioritize visible CMs in refreshOnViewListener

---
 edit/sections-editor.js | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/edit/sections-editor.js b/edit/sections-editor.js
index 6f71e83d..134397c4 100644
--- a/edit/sections-editor.js
+++ b/edit/sections-editor.js
@@ -647,11 +647,18 @@ function SectionsEditor() {
       xo.observe(cm.display.wrapper);
   }
 
+  /** @param {IntersectionObserverEntry[]} entries */
   function refreshOnViewListener(entries) {
-    for (const {isIntersecting, target} of entries) {
-      if (isIntersecting) {
-        target.CodeMirror.refresh();
-        xo.unobserve(target);
+    for (const e of entries) {
+      const r = e.isIntersecting && e.intersectionRect;
+      if (r) {
+        xo.unobserve(e.target);
+        const cm = e.target.CodeMirror;
+        if (r.bottom > 0 && r.top < window.innerHeight) {
+          cm.refresh();
+        } else {
+          setTimeout(() => cm.refresh());
+        }
       }
     }
   }