[Fix] Fixed occasional crash when closing tabs/windows. Closes #143

- disconnecting all signals/slots from widgets before deleting
  them to prevent invoking slots on deleted objects.

src/app/qupzilla.cpp

@@ -1484,9 +1484,28 @@ void QupZilla::closeEvent(QCloseEvent* event)
     }
 #endif
 
+    disconnectAllWidgets();
     event->accept();
 }
 
+void QupZilla::disconnectAllWidgets()
+{
+    // Disconnecting all important widgets before deleting this window
+    // so it cannot happen that slots will be invoked after the object
+    // is deleted.
+    // We have to do it this way, because ~QObject is deleting all child
+    // objects with plain delete - not deleteLater().
+
+    disconnect();
+    m_tabWidget->disconnect();
+    m_tabWidget->getTabBar()->disconnect();
+
+    foreach(WebTab * tab, m_tabWidget->allTabs()) {
+        WebView* view = tab->view();
+        view->disconnect();
+    }
+}
+
 bool QupZilla::quitApp()
 {
     if (m_sideBar.data()) {

src/app/qupzilla.h

@@ -210,9 +210,10 @@ private:
 
     void setupUi();
     void setupMenu();
-
     void addSideBar();
 
+    void disconnectAllWidgets();
+
     bool m_historyMenuChanged;
     bool m_bookmarksMenuChanged;
     bool m_isClosing;

src/webview/tabwidget.cpp

@@ -354,6 +354,7 @@ void TabWidget::closeTab(int index)
         tabBar()->setVisible(false);
     }
 
+    widget(index)->disconnect();
     widget(index)->deleteLater();
 }
 

src/webview/webview.cpp

@@ -388,6 +388,9 @@ TabWidget* WebView::tabWidget() const
     return 0;
 }
 
+// FIXME: Don't do this magic to get index of tab.
+// Implement setTabIndex() and call it from TabWidget (when creating and also from
+// tabMoved slot)
 int WebView::tabIndex() const
 {
     TabWidget* tabWid = tabWidget();
@@ -396,7 +399,10 @@ int WebView::tabIndex() const
     }
 
     int i = 0;
-    while (qobject_cast<WebTab*>(tabWid->widget(i))->view() != this) {
+    while (WebTab* wTab = qobject_cast<WebTab*>(tabWid->widget(i))) {
+        if (wTab && wTab->view() == this) {
+            break;
+        }
         i++;
     }
     return i;
@@ -1103,4 +1109,5 @@ bool WebView::eventFilter(QObject* obj, QEvent* event)
 
 WebView::~WebView()
 {
+    m_page->triggerAction(QWebPage::Stop);
 }