dail8859 · aniro · May 4, 2026 · May 4, 2026 · May 4, 2026 · May 4, 2026
diff --git a/src/ApplicationSettings.cpp b/src/ApplicationSettings.cpp
@@ -20,6 +20,7 @@
 
 #include <QApplication>
 #include <QFont>
+#include <QStyleHints>
 
 #define CREATE_SETTING(group, name, lname, type, default) \
 ApplicationSetting<type> name{#group "/" #name, default};\
@@ -38,6 +39,28 @@ ApplicationSetting<type> name{#group "/" #name, default};\
 ApplicationSettings::ApplicationSettings(QObject *parent)
     : QSettings{parent}
 {
+    // Translate user-facing theme changes and OS-level color-scheme changes
+    // into a single effectiveDarkModeChanged signal that consumers listen for.
+    connect(this, &ApplicationSettings::themeChanged, this, [this](ThemeMode) {
+        emit effectiveDarkModeChanged(effectiveDarkMode());
+    });
+    if (auto *hints = QGuiApplication::styleHints()) {
+        connect(hints, &QStyleHints::colorSchemeChanged, this, [this](Qt::ColorScheme) {
+            if (theme() == SystemTheme)
+                emit effectiveDarkModeChanged(effectiveDarkMode());
+        });
+    }
+}
+
+bool ApplicationSettings::effectiveDarkMode() const
+{
+    switch (theme()) {
+    case LightTheme: return false;
+    case DarkTheme:  return true;
+    case SystemTheme:
+    default:
+        return QGuiApplication::styleHints()->colorScheme() == Qt::ColorScheme::Dark;
+    }
 }
 
 CREATE_SETTING(Gui, ShowMenuBar, showMenuBar, bool, true)
@@ -71,3 +94,5 @@ CREATE_SETTING(Editor, AdditionalWordChars, additionalWordChars, QString, QStrin
 CREATE_SETTING(Editor, DefaultEOLMode, defaultEOLMode, QString, QStringLiteral(""))
 CREATE_SETTING(Editor, URLHighlighting, urlHighlighting, bool, true)
 CREATE_SETTING(Editor, ShowLineNumbers, showLineNumbers, bool, true)
+
+CREATE_SETTING(Gui, Theme, theme, ApplicationSettings::ThemeMode, ApplicationSettings::SystemTheme)
diff --git a/src/ApplicationSettings.h b/src/ApplicationSettings.h
@@ -76,6 +76,17 @@ class ApplicationSettings : public QSettings
     };
     Q_ENUM(DefaultDirectoryBehaviorEnum)
 
+    enum ThemeMode {
+        SystemTheme,
+        LightTheme,
+        DarkTheme
+    };
+    Q_ENUM(ThemeMode)
+
+    // Resolves Theme=System against the current QStyleHints color scheme.
+    bool effectiveDarkMode() const;
+    Q_SIGNAL void effectiveDarkModeChanged(bool dark);
+
     template <typename T>
     T get(const char *key, const T &defaultValue) const
     { return value(QLatin1String(key), defaultValue).template value<T>(); }
@@ -119,4 +130,6 @@ class ApplicationSettings : public QSettings
     DEFINE_SETTING(DefaultEOLMode, defaultEOLMode, QString)
     DEFINE_SETTING(URLHighlighting, urlHighlighting, bool)
     DEFINE_SETTING(ShowLineNumbers, showLineNumbers, bool)
+
+    DEFINE_SETTING(Theme, theme, ThemeMode)
 };
diff --git a/src/EditorManager.cpp b/src/EditorManager.cpp
@@ -128,6 +128,11 @@ EditorManager::EditorManager(ApplicationSettings *settings, QObject *parent)
             }
         }
     });
+
+    connect(settings, &ApplicationSettings::effectiveDarkModeChanged, this, [=](bool) {
+        for (auto &editor : getEditors())
+            applyEditorTheme(editor);
+    });
 }
 
 ScintillaNext *EditorManager::createEditor(const QString &name)
@@ -225,54 +230,18 @@ void EditorManager::setupEditor(ScintillaNext *editor)
 
     editor->setEdgeColour(0x80FFFF);
 
-    // https://www.scintilla.org/ScintillaDoc.html#ElementColours
-    // SC_ELEMENT_SELECTION_TEXT
-    // SC_ELEMENT_SELECTION_BACK
-    // SC_ELEMENT_SELECTION_ADDITIONAL_TEXT
-    // SC_ELEMENT_SELECTION_ADDITIONAL_BACK
-    // SC_ELEMENT_SELECTION_SECONDARY_TEXT
-    // SC_ELEMENT_SELECTION_SECONDARY_BACK
-    // SC_ELEMENT_SELECTION_INACTIVE_TEXT
-    editor->setElementColour(SC_ELEMENT_SELECTION_INACTIVE_BACK, 0xFFE0E0E0);
-    // SC_ELEMENT_CARET
-    // SC_ELEMENT_CARET_ADDITIONAL
-    editor->setElementColour(SC_ELEMENT_CARET_LINE_BACK, 0xFFFFE8E8);
-    editor->setElementColour(SC_ELEMENT_WHITE_SPACE, 0xFFD0D0D0);
-    // SC_ELEMENT_WHITE_SPACE_BACK
-    // SC_ELEMENT_HOT_SPOT_ACTIVE
-    // SC_ELEMENT_HOT_SPOT_ACTIVE_BACK
-    editor->setElementColour(SC_ELEMENT_FOLD_LINE, 0xFFA0A0A0);
-    // SC_ELEMENT_HIDDEN_LINE
-
     editor->setWhitespaceSize(2);
 
-    editor->setFoldMarginColour(true, 0xFFFFFF);
-    editor->setFoldMarginHiColour(true, 0xE9E9E9);
-
     editor->setAutomaticFold(SC_AUTOMATICFOLD_SHOW | SC_AUTOMATICFOLD_CLICK | SC_AUTOMATICFOLD_CHANGE);
     editor->markerEnableHighlight(true);
 
     editor->setCharsDefault();
     editor->setWordChars(editor->wordChars() + settings->additionalWordChars().toLatin1());
 
-    editor->styleSetFore(STYLE_DEFAULT, 0x000000);
-    editor->styleSetBack(STYLE_DEFAULT, 0xFFFFFF);
     editor->styleSetSize(STYLE_DEFAULT, settings->fontSize());
     editor->styleSetFont(STYLE_DEFAULT, settings->fontName().toUtf8().data());
-    editor->styleClearAll();
-
-    editor->styleSetFore(STYLE_LINENUMBER, 0x808080);
-    editor->styleSetBack(STYLE_LINENUMBER, 0xE4E4E4);
-    editor->styleSetBold(STYLE_LINENUMBER, false);
-
-    editor->styleSetFore(STYLE_BRACELIGHT, 0x0000FF);
-    editor->styleSetBack(STYLE_BRACELIGHT, 0xFFFFFF);
 
-    editor->styleSetFore(STYLE_BRACEBAD, 0x000080);
-    editor->styleSetBack(STYLE_BRACEBAD, 0xFFFFFF);
-
-    editor->styleSetFore(STYLE_INDENTGUIDE, 0xC0C0C0);
-    editor->styleSetBack(STYLE_INDENTGUIDE, 0xFFFFFF);
+    applyEditorTheme(editor);
 
     // STYLE_CONTROLCHAR
     // STYLE_CALLTIP
@@ -334,6 +303,55 @@ void EditorManager::setupEditor(ScintillaNext *editor)
     new HTMLAutoCompleteDecorator(editor);
 }
 
+void EditorManager::applyEditorTheme(ScintillaNext *editor)
+{
+    const bool dark = settings->effectiveDarkMode();
+
+    // Fold markers (not affected by styleClearAll)
+    for (int i = SC_MARKNUM_FOLDEREND; i <= SC_MARKNUM_FOLDEROPEN; ++i) {
+        editor->markerSetFore(i, dark ? 0x3C3C3C : 0xF3F3F3);
+        editor->markerSetBack(i, 0x808080);
+        editor->markerSetBackSelected(i, dark ? 0xCC7A00 : 0x0000FF);
+    }
+
+    // Element colors (ARGB 0xAARRGGBB; not affected by styleClearAll)
+    editor->setElementColour(SC_ELEMENT_SELECTION_INACTIVE_BACK, dark ? 0xFF3A3D41 : 0xFFE0E0E0);
+    editor->setElementColour(SC_ELEMENT_CARET_LINE_BACK,         dark ? 0xFF2A2D2E : 0xFFFFE8E8);
+    editor->setElementColour(SC_ELEMENT_WHITE_SPACE,             dark ? 0xFF505050 : 0xFFD0D0D0);
+    editor->setElementColour(SC_ELEMENT_FOLD_LINE,               dark ? 0xFF505050 : 0xFFA0A0A0);
+
+    // Fold margin (not affected by styleClearAll)
+    editor->setFoldMarginColour(true,   dark ? 0x1E1E1E : 0xFFFFFF);
+    editor->setFoldMarginHiColour(true, dark ? 0x252526 : 0xE9E9E9);
+
+    // STYLE_DEFAULT sets the base for styleClearAll()
+    editor->styleSetFore(STYLE_DEFAULT, dark ? 0xD4D4D4 : 0x000000);
+    editor->styleSetBack(STYLE_DEFAULT, dark ? 0x1E1E1E : 0xFFFFFF);
+    editor->styleClearAll();
+
+    // Named styles must be re-applied after any subsequent styleClearAll
+    // (Lua SetStyle does one when a language is loaded)
+    applyEditorNamedStyles(editor);
+}
+
+void EditorManager::applyEditorNamedStyles(ScintillaNext *editor)
+{
+    const bool dark = settings->effectiveDarkMode();
+
+    editor->styleSetFore(STYLE_LINENUMBER, dark ? 0x858585 : 0x808080);
+    editor->styleSetBack(STYLE_LINENUMBER, dark ? 0x252526 : 0xE4E4E4);
+    editor->styleSetBold(STYLE_LINENUMBER, false);
+
+    editor->styleSetFore(STYLE_BRACELIGHT, dark ? 0xD4D4D4 : 0x0000FF);
+    editor->styleSetBack(STYLE_BRACELIGHT, dark ? 0x1E1E1E : 0xFFFFFF);
+
+    editor->styleSetFore(STYLE_BRACEBAD,   dark ? 0x0000FF : 0x000080);
+    editor->styleSetBack(STYLE_BRACEBAD,   dark ? 0x1E1E1E : 0xFFFFFF);
+
+    editor->styleSetFore(STYLE_INDENTGUIDE, dark ? 0x404040 : 0xC0C0C0);
+    editor->styleSetBack(STYLE_INDENTGUIDE, dark ? 0x1E1E1E : 0xFFFFFF);
+}
+
 void EditorManager::purgeOldEditorPointers()
 {
     QMutableListIterator<QPointer<ScintillaNext>> it(editors);

diff --git a/src/EditorManager.h b/src/EditorManager.h
@@ -41,14 +41,18 @@ class EditorManager : public QObject
 
     void manageEditor(ScintillaNext *editor);
 
+    void applyEditorTheme(ScintillaNext *editor);
+    void applyEditorNamedStyles(ScintillaNext *editor);
+
+    QList<QPointer<ScintillaNext>> getEditors();
+
 signals:
     void editorCreated(ScintillaNext *editor);
     void editorClosed(ScintillaNext *editor);
 
 private:
     void setupEditor(ScintillaNext *editor);
     void purgeOldEditorPointers();
-    QList<QPointer<ScintillaNext>> getEditors();
     int detectEOLMode(ScintillaNext *editor) const;
 
     QList<QPointer<ScintillaNext>> editors;

diff --git a/src/NotepadNextApplication.cpp b/src/NotepadNextApplication.cpp
@@ -149,9 +149,12 @@ bool NotepadNextApplication::init()
     MarkerAppDecorator *mad = new MarkerAppDecorator(this);
     mad->setEnabled(true);
 
+    luaState->setVariable("dark_mode", settings->effectiveDarkMode());
     luaState->executeFile(":/scripts/init.lua");
     LuaExtension::Instance().Initialise(luaState->L, Q_NULLPTR);
 
+    connect(settings, &ApplicationSettings::effectiveDarkModeChanged, this, &NotepadNextApplication::refreshEditorTheme);
+
     createNewWindow();
     connect(editorManager, &EditorManager::editorCreated, window, &MainWindow::addEditor);
 
@@ -295,6 +298,10 @@ void NotepadNextApplication::setEditorLanguage(ScintillaNext *editor, const QStr
     getLuaState()->setVariable("skip_tabwidth", skipTabWidth);
 
     getLuaState()->execute("SetLanguage(languageName)");
+
+    // Restore line number, brace match, and indent guide colors that the
+    // Lua-side styleClearAll wiped.
+    editorManager->applyEditorNamedStyles(editor);
 }
 
 QString NotepadNextApplication::detectLanguage(ScintillaNext *editor) const
@@ -508,3 +515,14 @@ QStringList NotepadNextApplication::debugInfo() const
 
     return info;
 }
+
+void NotepadNextApplication::refreshEditorTheme()
+{
+    getLuaState()->setVariable("dark_mode", settings->effectiveDarkMode());
+    getLuaState()->execute("UpdateTheme()");
+
+    for (auto &editor : editorManager->getEditors()) {
+        if (!editor->languageName.isEmpty())
+            setEditorLanguage(editor, editor->languageName);
+    }
+}
diff --git a/src/NotepadNextApplication.h b/src/NotepadNextApplication.h
@@ -73,6 +73,9 @@ class NotepadNextApplication : public SingleApplication
 protected:
     bool event(QEvent *event) override;
 
+public slots:
+    void refreshEditorTheme();
+
 private slots:
     void saveSettings();
     void receiveInfoFromSecondaryInstance(quint32 instanceId, QByteArray message);

diff --git a/src/dialogs/MainWindow.cpp b/src/dialogs/MainWindow.cpp
@@ -42,6 +42,7 @@
 #include <QProcess>
 #include <QScreen>
 #include <QFontDatabase>
+#include <QPalette>
 
 
 #ifdef Q_OS_WIN
@@ -882,7 +883,7 @@ MainWindow::MainWindow(NotepadNextApplication *app) :
     languageInspectorDock->hide();
     addDockWidget(Qt::RightDockWidgetArea, languageInspectorDock);
 
-    LuaConsoleDock *luaConsoleDock = new LuaConsoleDock(app->getLuaState(), this);
+    LuaConsoleDock *luaConsoleDock = new LuaConsoleDock(app->getLuaState(), app->getSettings(), this);
     luaConsoleDock->hide();
     addDockWidget(Qt::BottomDockWidgetArea, luaConsoleDock);
 
@@ -914,6 +915,7 @@ MainWindow::MainWindow(NotepadNextApplication *app) :
     });
     connect(app->getSettings(), &ApplicationSettings::showToolBarChanged, ui->mainToolBar, &QToolBar::setVisible);
     connect(app->getSettings(), &ApplicationSettings::showStatusBarChanged, ui->statusBar, &QStatusBar::setVisible);
+    connect(app->getSettings(), &ApplicationSettings::effectiveDarkModeChanged, this, &MainWindow::applyStyleSheet);
     connect(ui->statusBar, &EditorInfoStatusBar::customContextMenuRequestedForEOLLabel, this, [=](const QPoint &pos){
         ui->menuEOLConversion->popup(pos);
     });
@@ -1799,10 +1801,56 @@ void MainWindow::applyStyleSheet()
 {
     qInfo(Q_FUNC_INFO);
 
+    auto *settings = app->getSettings();
+    const bool dark = settings->effectiveDarkMode();
+
+    if (settings->theme() == ApplicationSettings::SystemTheme) {
+        // Follow the desktop environment - leave the Qt-default palette alone.
+        // Qt 6.5+ already syncs the palette with QStyleHints::colorScheme().
+    } else {
+        // Explicit Light or Dark override - hardcoded palette so the app
+        // theme is independent of the system color scheme.
+        QPalette p;
+        if (dark) {
+            p.setColor(QPalette::Window,          QColor(0x1E, 0x1E, 0x1E));
+            p.setColor(QPalette::WindowText,      QColor(0xD4, 0xD4, 0xD4));
+            p.setColor(QPalette::Base,            QColor(0x25, 0x25, 0x26));
+            p.setColor(QPalette::AlternateBase,   QColor(0x2D, 0x2D, 0x2D));
+            p.setColor(QPalette::Text,            QColor(0xD4, 0xD4, 0xD4));
+            p.setColor(QPalette::Button,          QColor(0x3C, 0x3C, 0x3C));
+            p.setColor(QPalette::ButtonText,      QColor(0xD4, 0xD4, 0xD4));
+            p.setColor(QPalette::Highlight,       QColor(0x00, 0x7A, 0xCC));
+            p.setColor(QPalette::HighlightedText, QColor(0xFF, 0xFF, 0xFF));
+            p.setColor(QPalette::ToolTipBase,     QColor(0x25, 0x25, 0x26));
+            p.setColor(QPalette::ToolTipText,     QColor(0xD4, 0xD4, 0xD4));
+            p.setColor(QPalette::Link,            QColor(0x40, 0xA0, 0xFF));
+            p.setColor(QPalette::Disabled, QPalette::Text,       QColor(0x66, 0x66, 0x66));
+            p.setColor(QPalette::Disabled, QPalette::ButtonText, QColor(0x66, 0x66, 0x66));
+        } else {
+            p.setColor(QPalette::Window,          QColor(0xF0, 0xF0, 0xF0));
+            p.setColor(QPalette::WindowText,      QColor(0x00, 0x00, 0x00));
+            p.setColor(QPalette::Base,            QColor(0xFF, 0xFF, 0xFF));
+            p.setColor(QPalette::AlternateBase,   QColor(0xF7, 0xF7, 0xF7));
+            p.setColor(QPalette::Text,            QColor(0x00, 0x00, 0x00));
+            p.setColor(QPalette::Button,          QColor(0xE6, 0xE6, 0xE6));
+            p.setColor(QPalette::ButtonText,      QColor(0x00, 0x00, 0x00));
+            p.setColor(QPalette::Highlight,       QColor(0x33, 0x99, 0xFF));
+            p.setColor(QPalette::HighlightedText, QColor(0xFF, 0xFF, 0xFF));
+            p.setColor(QPalette::ToolTipBase,     QColor(0xFF, 0xFF, 0xDC));
+            p.setColor(QPalette::ToolTipText,     QColor(0x00, 0x00, 0x00));
+            p.setColor(QPalette::Link,            QColor(0x00, 0x00, 0xEE));
+            p.setColor(QPalette::Disabled, QPalette::Text,       QColor(0x99, 0x99, 0x99));
+            p.setColor(QPalette::Disabled, QPalette::ButtonText, QColor(0x99, 0x99, 0x99));
+        }
+        QApplication::setPalette(p);
+    }
+
+    // Targeted CSS for custom widgets (ADS dock tabs, QuickFindWidget, status bar)
+    const QString cssResource = dark ? QStringLiteral(":/stylesheets/npp-dark.css")
+                                     : QStringLiteral(":/stylesheets/npp.css");
     QString sheet;
-    QFile f(":/stylesheets/npp.css");
+    QFile f(cssResource);
     qInfo() << "Loading stylesheet:" << f.fileName();
-
     f.open(QFile::ReadOnly);
     sheet = f.readAll();
     f.close();

diff --git a/src/dialogs/PreferencesDialog.cpp b/src/dialogs/PreferencesDialog.cpp
@@ -44,6 +44,13 @@ PreferencesDialog::PreferencesDialog(ApplicationSettings *settings, QWidget *par
     MapSettingToCheckBox(ui->checkBoxMenuBar, &ApplicationSettings::showMenuBar, &ApplicationSettings::setShowMenuBar, &ApplicationSettings::showMenuBarChanged);
     MapSettingToCheckBox(ui->checkBoxToolBar, &ApplicationSettings::showToolBar, &ApplicationSettings::setShowToolBar, &ApplicationSettings::showToolBarChanged);
     MapSettingToCheckBox(ui->checkBoxStatusBar, &ApplicationSettings::showStatusBar, &ApplicationSettings::setShowStatusBar, &ApplicationSettings::showStatusBarChanged);
+    ui->comboBoxTheme->setCurrentIndex(static_cast<int>(settings->theme()));
+    connect(ui->comboBoxTheme, QOverload<int>::of(&QComboBox::currentIndexChanged), this, [=](int index) {
+        settings->setTheme(static_cast<ApplicationSettings::ThemeMode>(index));
+    });
+    connect(settings, &ApplicationSettings::themeChanged, this, [=](ApplicationSettings::ThemeMode mode) {
+        ui->comboBoxTheme->setCurrentIndex(static_cast<int>(mode));
+    });
     MapSettingToCheckBox(ui->checkBoxRecenterSearchDialog, &ApplicationSettings::centerSearchDialog, &ApplicationSettings::setCenterSearchDialog, &ApplicationSettings::centerSearchDialogChanged);
 
     MapSettingToGroupBox(ui->gbxRestorePreviousSession, &ApplicationSettings::restorePreviousSession, &ApplicationSettings::setRestorePreviousSession, &ApplicationSettings::restorePreviousSessionChanged);