Delete QObject::setParent() in the controller

To find places where we're setting parent on the controller instead
of in the view. Fix such case where the dock widget view
wasn't being parented to the frame view.

src/controllers/DockWidget.cpp

@@ -112,7 +112,7 @@ void DockWidget::addDockWidgetAsTab(DockWidget *other, InitialOption option)
         }
     }
 
-    other->setParent(nullptr);
+    other->view()->setParent(nullptr);
     frame->addWidget(other, option);
 }
 
@@ -384,6 +384,7 @@ QStringList DockWidget::affinities() const
 
 void DockWidget::show()
 {
+    // TODOv2: show wont be called. move to view instead.
     if (view()->isRootView() && (d->m_lastPosition->wasFloating() || !d->m_lastPosition->isValid())) {
         // Create the FloatingWindow already, instead of waiting for the show event.
         // This reduces flickering on some platforms
@@ -734,7 +735,7 @@ void DockWidget::Private::close()
 
     // Do some cleaning. Widget is hidden, but we must hide the tab containing it.
     if (Controllers::Frame *frame = this->frame()) {
-        q->setParent(nullptr);
+        q->QObject::setParent(nullptr);
         q->view()->setParent(nullptr);
         frame->removeWidget(q);