some code to deal with dark mode and colors inherited from OS

resources/scripts/github-actions/build-windows.ps1

@@ -24,7 +24,7 @@ if ($use_qt5 -eq "ON") {
   $qt_version = "5.15.2"
 }
 else {
-  $qt_version = "6.5.0"
+  $qt_version = "6.4.3"
 }
 
 $maria_version = "10.6.12"

src/librssguard/miscellaneous/skinfactory.cpp

@@ -48,12 +48,67 @@ void SkinFactory::loadCurrentSkin() {
 }
 
 bool SkinFactory::isStyleGoodForAlternativeStylePalette(const QString& style_name) const {
-  static QRegularExpression re = QRegularExpression("^(fusion|windows|qt[56]ct-style)$");
+  static QRegularExpression re = QRegularExpression(QSL("^(fusion|windows|qt[56]ct-style)$"));
 
   return re.match(style_name.toLower()).hasMatch();
 }
 
+// NOTE: Taken from "QPlatformThemePrivate" Qt class.
+// This is here because in Qt 6.5.0, they hardcoded
+// DARK palette if user has enabled "dark mode" in OS.
+QPalette qt_fusionPalette(bool darkAppearance) {
+  const QColor windowText = darkAppearance ? QColor(240, 240, 240) : Qt::black;
+  const QColor backGround = darkAppearance ? QColor(50, 50, 50) : QColor(239, 239, 239);
+  const QColor light = backGround.lighter(150);
+  const QColor mid = (backGround.darker(130));
+  const QColor midLight = mid.lighter(110);
+  const QColor base = darkAppearance ? backGround.darker(140) : Qt::white;
+  const QColor disabledBase(backGround);
+  const QColor dark = backGround.darker(150);
+  const QColor darkDisabled = QColor(209, 209, 209).darker(110);
+  const QColor text = darkAppearance ? windowText : Qt::black;
+  const QColor highlight = QColor(48, 140, 198);
+  const QColor hightlightedText = darkAppearance ? windowText : Qt::white;
+  const QColor disabledText = darkAppearance ? QColor(130, 130, 130) : QColor(190, 190, 190);
+  const QColor button = backGround;
+  const QColor shadow = dark.darker(135);
+  const QColor disabledShadow = shadow.lighter(150);
+  QColor placeholder = text;
+  placeholder.setAlpha(128);
+
+  QPalette fusionPalette(windowText, backGround, light, dark, mid, text, base);
+  fusionPalette.setBrush(QPalette::Midlight, midLight);
+  fusionPalette.setBrush(QPalette::Button, button);
+  fusionPalette.setBrush(QPalette::Shadow, shadow);
+  fusionPalette.setBrush(QPalette::HighlightedText, hightlightedText);
+
+  fusionPalette.setBrush(QPalette::Disabled, QPalette::Text, disabledText);
+  fusionPalette.setBrush(QPalette::Disabled, QPalette::WindowText, disabledText);
+  fusionPalette.setBrush(QPalette::Disabled, QPalette::ButtonText, disabledText);
+  fusionPalette.setBrush(QPalette::Disabled, QPalette::Base, disabledBase);
+  fusionPalette.setBrush(QPalette::Disabled, QPalette::Dark, darkDisabled);
+  fusionPalette.setBrush(QPalette::Disabled, QPalette::Shadow, disabledShadow);
+
+  fusionPalette.setBrush(QPalette::Active, QPalette::Highlight, highlight);
+  fusionPalette.setBrush(QPalette::Inactive, QPalette::Highlight, highlight);
+  fusionPalette.setBrush(QPalette::Disabled, QPalette::Highlight, QColor(145, 145, 145));
+
+  fusionPalette.setBrush(QPalette::PlaceholderText, placeholder);
+
+  if (darkAppearance) {
+    fusionPalette.setBrush(QPalette::Link, highlight);
+  }
+
+  return fusionPalette;
+}
+
 void SkinFactory::loadSkinFromData(const Skin& skin) {
+#if QT_VERSION >= 0x060500 // Qt >= 6.5.0
+  auto system_color_scheme = qApp->styleHints()->colorScheme();
+
+  qDebugNN << LOGSEC_GUI << "OS defines color scheme:" << QUOTE_W_SPACE_DOT(system_color_scheme);
+#endif
+
   QString style_name = qApp->settings()->value(GROUP(GUI), SETTING(GUI::Style)).toString();
   auto env = QProcessEnvironment::systemEnvironment();
   const QString env_forced_style = env.value(QSL("QT_STYLE_OVERRIDE"));
@@ -123,6 +178,14 @@ void SkinFactory::loadSkinFromData(const Skin& skin) {
     QToolTip::setPalette(pal);
     qApp->setPalette(pal);
   }
+  // NOTE: Very hacky way of avoiding automatic "dark mode"
+  // palettes in some styles. Also in light mode,
+  // colors are now derived from system.
+#if QT_VERSION >= 0x060500 // Qt >= 6.5.0
+  else /* if (qApp->styleHints()->colorScheme() == Qt::ColorScheme::Dark) */ {
+    qApp->setPalette(qt_fusionPalette(false));
+  }
+#endif
 
   if (!skin.m_rawData.isEmpty()) {
     if (qApp->styleSheet().simplified().isEmpty() && use_skin_colors) {