From 66185664e71b7cd65fa933467e338c665b2d5b88 Mon Sep 17 00:00:00 2001
From: Neil Hodgson <nyamatongwe@gmail.com>
Date: Mon, 13 Oct 2025 13:27:07 +1100
Subject: Fix Cocoa bidirectional mode crash when scrolled before start of
 document.

---
 doc/ScintillaHistory.html | 3 +++
 src/EditView.cxx          | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/doc/ScintillaHistory.html b/doc/ScintillaHistory.html
index 9d41f3cfa..65d6b9fcb 100644
--- a/doc/ScintillaHistory.html
+++ b/doc/ScintillaHistory.html
@@ -615,6 +615,9 @@
 	<a href="https://sourceforge.net/p/scintilla/bugs/2482/">Bug #2482</a>.
 	</li>
 	<li>
+	On Cocoa, fix crash with bidirectional mode when scrolled before start of document.
+	</li>
+	<li>
 	On Cocoa, use same default calltip colours as other platforms for consistency.
 	<a href="https://sourceforge.net/p/scintilla/bugs/2486/">Bug #2486</a>.
 	</li>
diff --git a/src/EditView.cxx b/src/EditView.cxx
index dddd84d94..3bf0a1fbb 100644
--- a/src/EditView.cxx
+++ b/src/EditView.cxx
@@ -602,7 +602,7 @@ void EditView::LayoutLine(const EditModel &model, Surface *surface, const ViewSt
 // Fill the LineLayout bidirectional data fields according to each char style
 
 void EditView::UpdateBidiData(const EditModel &model, const ViewStyle &vstyle, LineLayout *ll) {
-	if (model.BidirectionalEnabled()) {
+	if (model.BidirectionalEnabled() && (ll->numCharsInLine >= 0)) {
 		ll->EnsureBidiData();
 		for (int stylesInLine = 0; stylesInLine < ll->numCharsInLine; stylesInLine++) {
 			ll->bidiData->stylesFonts[stylesInLine] = vstyle.styles[ll->styles[stylesInLine]].font;
-- 
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