+ fix issue with cursor on viewer widget, prepare code for improved event handling

src/Gui/Quarter/QuarterWidget.cpp

@@ -754,27 +754,56 @@ void QuarterWidget::paintEvent(QPaintEvent* event)
 }
 
 bool QuarterWidget::viewportEvent(QEvent* event)
-{    
-     if( event->type() == QEvent::Paint || event->type() == QEvent::Resize) {
+{
+    //TODO: After 0.16 is out activate the code below.
+#if 1
+    if (event->type() == QEvent::Paint || event->type() == QEvent::Resize) {
+        return QGraphicsView::viewportEvent(event);
+    }
+    else if (event->type() == QEvent::MouseMove ||
+             event->type() == QEvent::Wheel ||
+             event->type() == QEvent::MouseButtonDblClick ||
+             event->type() == QEvent::MouseButtonRelease ||
+             event->type() == QEvent::MouseButtonPress) {
+        QMouseEvent* mouse = static_cast<QMouseEvent*>(event);
+        QGraphicsItem *item = itemAt(mouse->pos());
+        if (!item) {
+            return false;
+        }
+
         return QGraphicsView::viewportEvent(event);
-     }
-     else if(event->type() == QEvent::MouseMove
-            || event->type() == QEvent::Wheel
-            || event->type() == QEvent::MouseButtonDblClick
-            || event->type() == QEvent::MouseButtonRelease
-            || event->type() == QEvent::MouseButtonPress) {
-        
-          QMouseEvent* mouse = static_cast<QMouseEvent*>(event);
-          QGraphicsItem *item = itemAt(mouse->pos());
-          if(!item) {
-              return false;
-          }
-          return QGraphicsView::viewportEvent(event);
       }
+
      //if we return false the events get processed normally, this means they get passed to the quarter
      //event filters for processing in the scene graph. If we return true event processing stops here.
      return false;
-        
+#else
+    // If no item is selected still let the graphics scene handle it but
+    // additionally handle it by this viewer. This is e.g. needed when
+    // resizing a widget item because the cursor may already be outside
+    // this widget.
+    if (event->type() == QEvent::Wheel ||
+        event->type() == QEvent::MouseButtonDblClick ||
+        event->type() == QEvent::MouseButtonPress) {
+        QMouseEvent* mouse = static_cast<QMouseEvent*>(event);
+        QGraphicsItem *item = itemAt(mouse->pos());
+        if (!item) {
+            QGraphicsView::viewportEvent(event);
+            return false;
+        }
+    }
+    else if (event->type() == QEvent::MouseMove ||
+             event->type() == QEvent::MouseButtonRelease) {
+        QMouseEvent* mouse = static_cast<QMouseEvent*>(event);
+        QGraphicsScene* glScene = this->scene();
+        if (!(glScene && glScene->mouseGrabberItem())) {
+            QGraphicsView::viewportEvent(event);
+            return false;
+        }
+    }
+
+    return QGraphicsView::viewportEvent(event);
+#endif
 }
 
 /*!

src/Gui/View3DInventorViewer.cpp

@@ -2530,10 +2530,17 @@ void View3DInventorViewer::setCursorRepresentation(int modearg)
     // won't be changed as long as the user doesn't leave and enter
     // the canvas. To fix this we explicitly set Qt::WA_UnderMouse
     // if the mouse is inside the canvas.
-    QWidget* w = this->getGLWidget();
+    QWidget* glWindow = this->getGLWidget();
 
-    if (w && w->rect().contains(QCursor::pos()))
-        w->setAttribute(Qt::WA_UnderMouse);
+    // When a widget is added to the QGraphicsScene and the user
+    // hovered over it the 'WA_SetCursor' attribute is set to the
+    // GL widget but never reset and thus would cause that the
+    // cursor on this widget won't be set.
+    if (glWindow)
+        glWindow->setAttribute(Qt::WA_SetCursor, false);
+
+    if (glWindow && glWindow->rect().contains(QCursor::pos()))
+        glWindow->setAttribute(Qt::WA_UnderMouse);
 
     switch (modearg) {
     case NavigationStyle::IDLE:

src/Mod/Sandbox/Gui/GLGraphicsView.cpp

@@ -111,6 +111,21 @@ void GraphicsView::resizeEvent(QResizeEvent *event)
     QGraphicsView::resizeEvent(event);
 }
 
+
+//QDialog *dialog = new QDialog(0, Qt::Window | Qt::CustomizeWindowHint | Qt::WindowTitleHint);
+
+////dialog->setWindowOpacity(0.8);
+//dialog->setWindowTitle(tr("Titel"));
+//dialog->setLayout(new QVBoxLayout);
+//dialog->layout()->addWidget(new QLabel(tr("Use mouse wheel to zoom model, and click and drag to rotate model")));
+//dialog->layout()->addWidget(new QLabel(tr("Move the sun around to change the light position")));
+//dialog->layout()->addWidget(new QSpinBox);
+
+//QGraphicsScene* scene = _viewer->scene();
+//QGraphicsProxyWidget* g1 = scene->addWidget(dialog);
+//g1->setWindowFlags(Qt::Window | Qt::CustomizeWindowHint | Qt::WindowTitleHint);
+
+
 // ----------------------------------------------------------------------------
 
 class SceneEventFilter::Private