Gui: [skip ci] wheel event filter for combo boxes

src/Gui/Application.cpp

@@ -1976,6 +1976,12 @@ void Application::runApplication(void)
     if (size >= 16) // must not be lower than this
         mw.setIconSize(QSize(size,size));
 
+    // filter wheel events for combo boxes
+    if (hGrp->GetBool("ComboBoxWheelEventFilter", false)) {
+        WheelEventFilter* filter = new WheelEventFilter(&mainApp);
+        mainApp.installEventFilter(filter);
+    }
+
 #if defined(HAVE_QT5_OPENGL)
     {
         QWindow window;

src/Gui/GuiApplication.cpp

@@ -27,6 +27,7 @@
 # include <sstream>
 # include <stdexcept>
 # include <QByteArray>
+# include <QComboBox>
 # include <QDataStream>
 # include <QDebug>
 # include <QFileInfo>
@@ -304,4 +305,19 @@ void GUISingleApplication::processMessages()
     Q_EMIT messageReceived(msg);
 }
 
+// ----------------------------------------------------------------------------
+
+WheelEventFilter::WheelEventFilter(QObject* parent)
+  : QObject(parent)
+{
+}
+
+bool WheelEventFilter::eventFilter(QObject* obj, QEvent* ev)
+{
+    if (qobject_cast<QComboBox*>(obj) && ev->type() == QEvent::Wheel)
+        return true;
+    return false;
+}
+
+
 #include "moc_GuiApplication.cpp"

src/Gui/GuiApplication.h

@@ -83,6 +83,15 @@ private:
     QScopedPointer<Private> d_ptr;
 };
 
+class WheelEventFilter : public QObject
+{
+    Q_OBJECT
+
+public:
+    WheelEventFilter(QObject* parent);
+    bool eventFilter(QObject* obj, QEvent* ev);
+};
+
 }
 
 #endif // GUI_APPLICATION_H