Revert "MAYA-131102: Fixing Qt issues related to docking"

Revert Senthil's temporary fix to QDockWidget docking which caused
crashes and showed orphaned empty QDockWidgetGroupWindow (which should
never show).

Reasoning: We are pulling in Qt's official fixes for this and some other
QDockWidget bugs.

Senthils fix that this reverts went into Maya 2025 release (the .0 release).
The Qt changes after this are intended to go into Maya 2025.1 release.

This reverts commit 9f02de8.

src/widgets/widgets/qmainwindowlayout.cpp

@@ -35,8 +35,6 @@
 #include <qmap.h>
 #include <qtimer.h>
 #include <qpointer.h>
-#include <qobject.h>
-#include <qaction.h>
 
 #ifndef QT_NO_DEBUG_STREAM
 #  include <qdebug.h>
@@ -266,20 +264,6 @@ bool QDockWidgetGroupWindow::event(QEvent *e)
         if (QDockWidget *dw = activeTabbedDockWidget()) {
             dw->close();
             adjustFlags();
-            // when all child QDockWidgets' are closed, this QDockWidgetGroupWindow will be hidden
-            // after receiving the `LayoutRequest` event. This causes subsequent call to show
-            // on the current QDockWidget to fail. Hence, adding a connection to the 
-            // QDockWidget's toggle action to re-show this QDockWidgetGroupWindow along with the 
-            // current QDockWidget.
-            m_widgetConnections[dw] = connect(dw->toggleViewAction(), &QAction::toggled, [this, dw]() {
-                // show this QDockWidgetGroupWindow before showing the child QDockWidget.
-                show();
-                dw->show();
-                // once at least one child becomes visible, clear all listeners since we no longer need them..
-                for (const auto& pair : m_widgetConnections)
-                    disconnect(pair.second);
-                m_widgetConnections.clear();
-            });
         }
 #endif
         return true;
@@ -304,10 +288,6 @@ bool QDockWidgetGroupWindow::event(QEvent *e)
         if (qobject_cast<QDockWidget *>(static_cast<QChildEvent*>(e)->child()))
             adjustFlags();
         break;
-    case QEvent::ChildRemoved:
-        if (auto widget = qobject_cast<QDockWidget *>(static_cast<QChildEvent*>(e)->child()))
-            m_widgetConnections.erase(widget);
-        break;
     case QEvent::LayoutRequest:
         // We might need to show the widget again
         destroyOrHideIfEmpty();
@@ -2597,7 +2577,70 @@ QLayoutItem *QMainWindowLayout::unplug(QWidget *widget, bool group)
 
             // unplug the widget first
             dockWidget->d_func()->unplug(widget->geometry());
-            return item;
+
+            // Create a floating tab, copy properties and generate layout info
+            QDockWidgetGroupWindow *floatingTabs = createTabbedDockWindow();
+            const QInternal::DockPosition dockPos = groupWindow->layoutInfo()->dockPos;
+            QDockAreaLayoutInfo *info = floatingTabs->layoutInfo();
+
+            const QTabBar::Shape shape = tabwidgetPositionToTabBarShape(dockWidget);
+
+            // Populate newly created DockAreaLayoutInfo of floating tabs
+            *info = QDockAreaLayoutInfo(&layoutState.dockAreaLayout.sep, dockPos,
+                                        Qt::Horizontal, shape,
+                                        layoutState.mainWindow);
+
+            // Create tab and hide it as group window contains only one widget
+            info->tabbed = true;
+            info->tabBar = getTabBar();
+            info->tabBar->hide();
+            updateGapIndicator();
+
+            // Reparent it to a QDockWidgetGroupLayout
+            floatingTabs->setGeometry(dockWidget->geometry());
+
+            // Append reference to floatingTabs to the dock's item_list
+            parentItem.widgetItem = new QDockWidgetGroupWindowItem(floatingTabs);
+            layoutState.dockAreaLayout.docks[dockPos].item_list.append(parentItem);
+
+            // use populated parentItem to set reference to dockWidget as the first item in own list
+            parentItem.widgetItem = new QDockWidgetItem(dockWidget);
+            info->item_list = {parentItem};
+
+            // Add non-gap items of the dock to the tab bar
+            for (const auto &listItem : layoutState.dockAreaLayout.docks[dockPos].item_list) {
+                if (listItem.GapItem || !listItem.widgetItem)
+                    continue;
+                info->tabBar->addTab(listItem.widgetItem->widget()->objectName());
+            }
+
+            // Re-parent and fit
+            floatingTabs->setParent(layoutState.mainWindow);
+            floatingTabs->layoutInfo()->fitItems();
+            floatingTabs->layoutInfo()->apply(dockOptions & QMainWindow::AnimatedDocks);
+            groupWindow->layoutInfo()->fitItems();
+            groupWindow->layoutInfo()->apply(dockOptions & QMainWindow::AnimatedDocks);
+            dockWidget->d_func()->tabPosition = layoutState.mainWindow->tabPosition(toDockWidgetArea(dockPos));
+            info->reparentWidgets(floatingTabs);
+            dockWidget->setParent(floatingTabs);
+            info->updateTabBar();
+
+            // Show the new item
+            const QList<int> path = layoutState.indexOf(floatingTabs);
+            QRect r = layoutState.itemRect(path);
+            savedState = layoutState;
+            savedState.fitLayout();
+
+            // Update gap, fix orientation, raise and show
+            currentGapPos = path;
+            currentGapRect = r;
+            updateGapIndicator();
+            fixToolBarOrientation(parentItem.widgetItem, currentGapPos.at(1));
+            floatingTabs->show();
+            floatingTabs->raise();
+
+            qCDebug(lcQpaDockWidgets) << "Unplugged from floating dock:" << widget << "from" << parentItem.widgetItem;
+            return parentItem.widgetItem;
         }
     }
 #endif
@@ -2794,18 +2837,10 @@ void QMainWindowLayout::hover(QLayoutItem *hoverTarget,
                     info->tabBar = getTabBar();
                     info->tabbed = true;
                     QLayout *parentLayout = dropTo->parentWidget()->layout();
-                    auto parentItem = QDockAreaLayoutItem(parentLayout->takeAt(parentLayout->indexOf(dropTo)));
-                    if (!parentItem.widgetItem)
-                        parentItem.widgetItem = new QDockWidgetItem(dropTo);
-                    info->item_list.append(parentItem);
-
-                    auto oldGroupWindow = qobject_cast<QDockWidgetGroupWindow *>(dropTo->parent());
-                    dropTo->setParent(floatingTabs);
-                    // just an early cleanup to if there are no other children.
-                    if (oldGroupWindow) {
-                        oldGroupWindow->destroyOrHideIfEmpty();
-                    }
+                    info->item_list.append(
+                        QDockAreaLayoutItem(parentLayout->takeAt(parentLayout->indexOf(dropTo))));
 
+                    dropTo->setParent(floatingTabs);
                     qCDebug(lcQpaDockWidgets) << "Wrapping" << widget << "into floating tabs" << floatingTabs;
                     w = floatingTabs;
                 }

src/widgets/widgets/qmainwindowlayout_p.h

@@ -38,7 +38,6 @@
 #include "qtoolbararealayout_p.h"
 #endif
 #include <QtCore/qloggingcategory.h>
-#include <unordered_map>
 
 QT_REQUIRE_CONFIG(mainwindow);
 
@@ -336,7 +335,6 @@ class Q_AUTOTEST_EXPORT QDockWidgetGroupWindow : public QWidget
 
 private:
     QSize m_removedFrameSize;
-    std::unordered_map<QDockWidget*, QMetaObject::Connection> m_widgetConnections;
 };
 
 // This item will be used in the layout for the gap item. We cannot use QWidgetItem directly