fixed parent of DropBox to avoid problems with hiding it

modules/gui/src/panels/panel_bar.cc

@@ -41,7 +41,7 @@ PanelBar::PanelBar(QWidget* parent) :
   view_mode_menu_(new QMenu("View Mode",this)),
   current_view_mode_(NULL),
   widget_states_(),
-  drop_box_(new DropBox(this)),
+  drop_box_(new DropBox), // DropBox having no parent is done on purpose (otherwise it will not hide properly)
   show_action_(new QAction(this))
 {
   connect(view_mode_menu_,SIGNAL(triggered(QAction*)),this,SLOT(ChangeViewMode(QAction*)));
@@ -62,6 +62,11 @@ PanelBar::PanelBar(QWidget* parent) :
   this->addAction(show_action_);
 }
 
+PanelBar::~PanelBar()
+{
+  delete drop_box_; // manually destroy drop_box_ widget, as it has no parent.
+}
+
 void PanelBar::AddWidget(Widget* widget, bool is_hidden)
 {
   int index = this->GetIndex(widget);

modules/gui/src/panels/panel_bar.hh

@@ -54,6 +54,7 @@ class DLLEXPORT_OST_GUI PanelBar : public Widget {
   Q_OBJECT
 public:
   PanelBar(QWidget* parent);
+  virtual ~PanelBar();
 
   virtual bool Save(const QString& prefix);
   virtual bool Restore(const QString& prefix);