Fix #11032 flickering when switching to Part Design

* Remove unneeded timer on taskview updates to fix #11032

* Remove obsoleted class member

src/Gui/TaskView/TaskView.cpp

@@ -301,9 +301,6 @@ TaskView::TaskView(QWidget *parent)
         (std::bind(&Gui::TaskView::TaskView::slotRedoDocument, this, sp::_1));
     //NOLINTEND
 
-    this->timer = new QTimer(this);
-    this->timer->setSingleShot(true);
-    QObject::connect(this->timer, &QTimer::timeout, [this](){onUpdateWatcher();});
     updateWatcher();
 }
 
@@ -609,11 +606,6 @@ void TaskView::removeDialog()
 }
 
 void TaskView::updateWatcher(void)
-{
-    this->timer->start(200);
-}
-
-void TaskView::onUpdateWatcher(void)
 {
     if (ActiveCtrl || ActiveDialog)
         return;
@@ -623,7 +615,6 @@ void TaskView::onUpdateWatcher(void)
         if (panel && panel->ActiveWatcher.size())
             takeTaskWatcher(panel);
     }
-    this->timer->stop();
 
     // In case a child of the TaskView has the focus and get hidden we have
     // to make sure to set the focus on a widget that won't be hidden or

src/Gui/TaskView/TaskView.h

@@ -171,7 +171,6 @@ protected Q_SLOTS:
     void reject();
     void helpRequested();
     void clicked (QAbstractButton * button);
-    void onUpdateWatcher();
 
 private:
     void triggerMinimumSizeHint();
@@ -200,7 +199,6 @@ protected:
     QSint::ActionPanel* taskPanel;
     TaskDialog *ActiveDialog;
     TaskEditControl *ActiveCtrl;
-    QTimer *timer;
 
     Connection connectApplicationActiveDocument;
     Connection connectApplicationDeleteDocument;