Use Breeze style in Flatpak

client/main.cpp

@@ -23,10 +23,12 @@
 #include <QtCore/QCommandLineParser>
 #include <QtCore/QDebug>
 #include <QtCore/QStandardPaths>
+#include <QtWidgets/QStyleFactory>
 
 #include "networksettings.h"
 #include "mainwindow.h"
 #include "activitydetector.h"
+#include "linuxutils.h"
 #include <settings.h>
 
 void loadTranslations(
@@ -93,6 +95,22 @@ int main( int argc, char* argv[] )
         QApplication::setFont(font);
     }
 
+#if defined Q_OS_UNIX && !defined Q_OS_MAC
+    const auto useBreezeStyle = Quotient::Settings().get("UI/use_breeze_style", inFlatpak());
+
+    // Set style to Breeze since Qt applications defaults to
+    // a very ugly Fusion style in Flatpak outside KDE
+    if (useBreezeStyle)
+    {
+        // Set icon theme as well to have uniform design
+        QApplication::setStyle("Breeze");
+        QIcon::setThemeName("breeze");
+#if QT_VERSION >= QT_VERSION_CHECK(5, 12, 0)
+        QIcon::setFallbackThemeName("breeze");
+#endif
+    }
+#endif
+
     // We should not need to do the following, as quitOnLastWindowClosed is
     // set to "true" by default; might be a bug, see
     // https://forum.qt.io/topic/71112/application-does-not-quit

client/mainwindow.cpp

@@ -436,6 +436,14 @@ void MainWindow::createMenu()
         else
             defaultLayout->setChecked(true);
     }
+#if defined Q_OS_UNIX && !defined Q_OS_MAC
+    addTimelineOptionCheckbox(
+        settingsMenu,
+        tr("Use Breeze style (requires restart)"),
+        tr("Force use Breeze style and icon theme"),
+        QStringLiteral("use_breeze_style"), inFlatpak()
+    );
+#endif
     addTimelineOptionCheckbox(
         settingsMenu,
         tr("Use shuttle scrollbar (requires restart)"),