Added custom events for changing icon theme in Linux because not all widgets are redrawn,

src/gui/formmain.cpp

@@ -1,5 +1,9 @@
+// for testing
+#include <QMessageBox>
+
 #include "gui/formmain.h"
 #include "gui/formsettings.h"
+#include "gui/themefactory.h"
 #include "core/settings.h"
 #include "qtsingleapplication/qtsingleapplication.h"
 
@@ -29,6 +33,22 @@ void FormMain::cleanupResources() {
   qDebug("Cleaning up resources before the application exits.");
 }
 
+#if defined(Q_OS_LINUX)
+bool FormMain::event(QEvent *event) {
+  if (event->type() == ThemeFactoryEvent::type()) {
+    // Handle the change of icon theme.
+    setupIcons();
+    return true;
+  }
+
+  return QMainWindow::event(event);
+}
+
+void FormMain::setupIcons() {
+  // NOTE: Call QIcon::fromTheme for all needed widgets here.
+}
+#endif
+
 void FormMain::createConnections() {
   // Menu "File" connections.
   connect(m_ui->m_actionQuit, &QAction::triggered, this, &FormMain::quit);

src/gui/formmain.h

@@ -16,6 +16,13 @@ class FormMain : public QMainWindow {
   protected:
     void createConnections();
 
+#if defined(Q_OS_LINUX)
+    bool event(QEvent *event);
+
+    // Sets up proper icons for this widget.
+    void setupIcons();
+#endif
+
   public slots:
     void processExecutionMessage(const QString &message);
     void quit();

src/gui/themefactory.cpp

@@ -4,10 +4,36 @@
 #include <QApplication>
 
 #include "gui/themefactory.h"
+#include "qtsingleapplication/qtsingleapplication.h"
 #include "core/settings.h"
 #include "core/defs.h"
 
 
+QEvent::Type ThemeFactoryEvent::m_typeOfEvent = QEvent::None;
+
+//
+// ThemeFactoryEvent class
+//
+
+ThemeFactoryEvent::ThemeFactoryEvent() : QEvent(ThemeFactoryEvent::type()) {
+}
+
+ThemeFactoryEvent::~ThemeFactoryEvent() {
+}
+
+QEvent::Type ThemeFactoryEvent::type()  {
+  if (m_typeOfEvent == QEvent::None) {
+    m_typeOfEvent = static_cast<QEvent::Type>(QEvent::registerEventType(2000));
+  }
+
+  return m_typeOfEvent;
+}
+
+
+//
+// ThemeFactory class
+//
+
 ThemeFactory::ThemeFactory() {
 }
 
@@ -64,6 +90,15 @@ void ThemeFactory::loadCurrentIconTheme() {
   else {
     qDebug("Loading theme '%s'.", qPrintable(theme_name));
     QIcon::setThemeName(theme_name);
+
+    // In Linux, we need to deliver custom event for all widgets
+    // to make sure they get a chance to redraw their icons.
+#if defined(Q_OS_LINUX)
+    foreach (QWidget *widget, QtSingleApplication::allWidgets()) {
+      QtSingleApplication::postEvent((QObject*) widget,
+                                     new ThemeFactoryEvent());
+    }
+#endif
   }
 }
 

src/gui/themefactory.h

@@ -2,6 +2,7 @@
 #define THEMEFACTORY_H
 
 #include <QString>
+#include <QEvent>
 
 
 class ThemeFactory {
@@ -36,4 +37,19 @@ class ThemeFactory {
     static void setCurrentIconTheme(const QString &theme_name);
 };
 
+class ThemeFactoryEvent : public QEvent {
+  public:
+    enum Type {
+      IconThemeChange = 2000
+    };
+
+    ThemeFactoryEvent();
+    virtual ~ThemeFactoryEvent();
+
+    static QEvent::Type type();
+
+  private:
+    static QEvent::Type m_typeOfEvent;
+};
+
 #endif // THEMEFACTORY_H