panels: fixed bug that added panel to list twice and led to double-free

app/panel/panelmanager.cpp

@@ -35,12 +35,10 @@ PanelManager::PanelManager(QObject *parent) :
 
 void PanelManager::DeleteAllPanels()
 {
-  foreach (PanelWidget* panel, focus_history_) {
-    // We don't need to run this signal anymore since we're destroying and clearing everything
-    disconnect(panel, &PanelWidget::destroyed, this, &PanelManager::PanelDestroyed);
-    delete panel;
-  }
+  // Prevent any confusion regarding focus history by clearing it first
+  QList<PanelWidget*> copy = focus_history_;
   focus_history_.clear();
+  qDeleteAll(copy);
 }
 
 const QList<PanelWidget *> &PanelManager::panels()

app/panel/panelmanager.h

@@ -175,18 +175,26 @@ T *PanelManager::CreatePanel(QWidget *parent)
 {
   T* panel = new T(parent);
 
-  panel->SetMovementLocked(locked_);
-
-  // Sane default for panel geometry
-  panel->resize(parent->size() / 3);
-  panel->move(panel->mapFromGlobal(parent->mapToGlobal(parent->pos())));
-
-  // Connect destroy signal so we can remove it from focus history
-  connect(panel, &PanelWidget::destroyed, this, &PanelManager::PanelDestroyed);
-
   // Add panel to the bottom of the focus history
   focus_history_.append(panel);
 
+  panel->SetMovementLocked(locked_);
+
+  // Sane default for panel size
+  panel->resize(parent->size() / 3);
+
+  // We're about to center the panel relative to the parent (usually the main window), but for some
+  // reason this requires the panel to be shown first.
+  panel->show();
+
+  // Center the panel relative to the parent
+  QPoint parent_center = panel->mapFromGlobal(parent->mapToGlobal(parent->rect().center()));
+  QPoint panel_center = panel->rect().center();
+  panel->move(parent_center - panel_center);
+
+  // Connect destroy signal so we can remove it from focus history
+  connect(panel, &PanelWidget::destroyed, this, &PanelManager::PanelDestroyed, Qt::DirectConnection);
+
   return panel;
 }