Adds macOS theme switch listening

src/app/Application.cpp

@@ -142,8 +142,7 @@ Application::Application(int &argc, char **argv, bool haltOnParseError)
 
   // Initialize theme.
   mTheme.reset(Theme::create(parser.value("theme")));
-  setStyle(mTheme->style());
-  setStyleSheet(mTheme->styleSheet());
+  applyTheme();
 
 #if defined(Q_OS_WIN)
   // Set default font style and hinting.
@@ -488,4 +487,9 @@ void Application::handleSslErrors(QNetworkReply *reply,
     reply->ignoreSslErrors(errors);
     settings.setValue("ssl/ignore", true);
   }
-}
+}
+
+void Application::applyTheme() {
+  setStyle(mTheme->style());
+  setStyleSheet(mTheme->styleSheet());
+}

src/app/Application.h

@@ -27,6 +27,7 @@ class Application : public QApplication {
   void autoUpdate();
   bool restoreWindows();
   bool runSingleInstance();
+  void applyTheme();
 
   static bool isInTest();
   static void setInTest();

src/ui/MainWindow.cpp

@@ -21,6 +21,7 @@
 #include "git/Repository.h"
 #include "git/Config.h"
 #include "git/Submodule.h"
+#include "app/Application.h"
 #include <QApplication>
 #include <QCloseEvent>
 #include <QGuiApplication>
@@ -589,3 +590,13 @@ QString MainWindow::windowGroup() const {
   QByteArray hash = QCryptographicHash::hash(group, QCryptographicHash::Md5);
   return QString::fromUtf8(hash.toHex());
 }
+
+void MainWindow::changeEvent(QEvent *e) {
+  if (e->type() == QEvent::PaletteChange) {
+    Application *app = qobject_cast<Application *>(QApplication::instance());
+    if (app)
+      app->applyTheme();
+  }
+
+  QMainWindow::changeEvent(e);
+}

src/ui/MainWindow.h

@@ -62,6 +62,7 @@ class MainWindow : public QMainWindow {
   void closeEvent(QCloseEvent *event) override;
   void dragEnterEvent(QDragEnterEvent *event) override;
   void dropEvent(QDropEvent *event) override;
+  void changeEvent(QEvent *event) override;
 
 private:
   void updateTabNames();