From 724429a7c661eeafe3094a049f747267d0496a69 Mon Sep 17 00:00:00 2001
From: Neil <nyamatongwe@gmail.com>
Date: Mon, 8 Dec 2025 14:38:07 +1100
Subject: Bug [#2488]. Fix SCI_SETSELECTIONNSTART and SCI_SETSELECTIONNEND.

---
 src/Editor.cxx    |  4 ++--
 src/Selection.cxx | 28 ++++++++++++++++++++++++++++
 src/Selection.h   |  2 ++
 3 files changed, 32 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/Editor.cxx b/src/Editor.cxx
index e7a309e67..1ad99c3ca 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -6178,11 +6178,11 @@ void Editor::SetSelectionNMessage(Message iMessage, uptr_t wParam, sptr_t lParam
 		break;
 
 	case Message::SetSelectionNStart:
-		sel.Range(wParam).anchor.SetPosition(lParam);
+		sel.Range(wParam).StartSet(SelectionPosition(lParam));
 		break;
 
 	case Message::SetSelectionNEnd:
-		sel.Range(wParam).caret.SetPosition(lParam);
+		sel.Range(wParam).EndSet(SelectionPosition(lParam));
 		break;
 
 	default:
diff --git a/src/Selection.cxx b/src/Selection.cxx
index 967033bff..e8d0148f5 100644
--- a/src/Selection.cxx
+++ b/src/Selection.cxx
@@ -182,6 +182,34 @@ SelectionSegment SelectionRange::Intersect(SelectionSegment check) const noexcep
 	};
 }
 
+void SelectionRange::StartSet(SelectionPosition sp) noexcept {
+	if (anchor <= caret) {
+		anchor = sp;
+		if (caret < anchor) {
+			caret = anchor;
+		}
+	} else {
+		caret = sp;
+		if (anchor < caret) {
+			anchor = caret;
+		}
+	}
+}
+
+void SelectionRange::EndSet(SelectionPosition sp) noexcept {
+	if (caret >= anchor) {
+		caret = sp;
+		if (anchor > caret) {
+			anchor = caret;
+		}
+	} else {
+		anchor = sp;
+		if (caret > anchor) {
+			caret = anchor;
+		}
+	}
+}
+
 void SelectionRange::Swap() noexcept {
 	std::swap(caret, anchor);
 }
diff --git a/src/Selection.h b/src/Selection.h
index 1a57d2e78..0b3bb9159 100644
--- a/src/Selection.h
+++ b/src/Selection.h
@@ -156,6 +156,8 @@ struct SelectionRange {
 	SelectionPosition End() const noexcept {
 		return (anchor < caret) ? caret : anchor;
 	}
+	void StartSet(SelectionPosition sp) noexcept;
+	void EndSet(SelectionPosition sp) noexcept;
 	void Swap() noexcept;
 	bool Trim(SelectionRange range) noexcept;
 	void Truncate(Sci::Position length) noexcept;
-- 
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