When closing a session, don't close the whole window if there are splits

When closing a session, we check if that is the last tab, and make the code
close the whole window, but we also need to make sure it's the last view,
i.e. no split views.

CCBUG: 440976
FIXED-IN: 21.12

src/ViewManager.cpp

@@ -494,9 +494,9 @@ void ViewManager::sessionFinished()
         return;
     }
 
-    // The last session/tab? emit empty() so that close() is called in
-    // MainWindow, fixes #432077
-    if (_viewContainer->count() == 1) {
+    // The last session/tab, and only one view (no splits), emit empty()
+    // so that close() is called in MainWindow, fixes #432077
+    if (_viewContainer->count() == 1 && _viewContainer->currentTabViewCount() == 1) {
         Q_EMIT empty();
         return;
     }

src/widgets/ViewContainer.cpp

@@ -144,6 +144,15 @@ ViewSplitter *TabbedViewContainer::viewSplitterAt(int index)
     return qobject_cast<ViewSplitter*>(widget(index));
 }
 
+int TabbedViewContainer::currentTabViewCount()
+{
+    if (auto *splitter = activeViewSplitter()) {
+        return splitter->findChildren<TerminalDisplay*>().count();
+    }
+
+    return 1;
+}
+
 void TabbedViewContainer::moveTabToWindow(int index, QWidget *window)
 {
     auto splitter = viewSplitterAt(index);

src/widgets/ViewContainer.h

@@ -135,6 +135,12 @@ public:
      */
     ViewSplitter *viewSplitterAt(int index);
 
+    /**
+     * Returns the number of split views (i.e. TerminalDisplay widgets)
+     * in this tab; if there are no split views, 1 is returned.
+     */
+    int currentTabViewCount();
+
     void connectTerminalDisplay(TerminalDisplay *display);
     void disconnectTerminalDisplay(TerminalDisplay *display);
     void moveTabLeft();