Prevent setFocus() recursion when application focus changes.

[nickdademo]

It is possible to create a setFocus() recursion under the following conditions:

CDockManager::FocusHighlighting = true
CDockManager::eConfigFlag::AllTabsHaveCloseButton = true
CDockManager::eConfigFlag::TabCloseButtonIsToolButton = true

with one dock widget set as the central widget and the other docks tabbed in the same area.

Reproduced with CentralWidgetExample:

[nickdademo]

This occurs because both focusedOld and focusedNow are close buttons - resulting in a never-ending setFocus loop.

Modified demo code to reproduce:

CMainWindow::CMainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::CMainWindow)
{
    ui->setupUi(this);
    CDockManager::setConfigFlag(CDockManager::OpaqueSplitterResize, true);
    CDockManager::setConfigFlag(CDockManager::XmlCompressionEnabled, false);
    CDockManager::setConfigFlag(CDockManager::FocusHighlighting, true);
    CDockManager::setConfigFlag(CDockManager::AllTabsHaveCloseButton, true); // ADDED
    CDockManager::setConfigFlag(CDockManager::TabCloseButtonIsToolButton, true); // ADDED
    DockManager = new CDockManager(this);

    // Set central widget
    QPlainTextEdit* w = new QPlainTextEdit();
	w->setPlaceholderText("This is the central editor. Enter your text here.");
    CDockWidget* CentralDockWidget = new CDockWidget("CentralWidget");
    CentralDockWidget->setWidget(w);
    auto* CentralDockArea = DockManager->setCentralWidget(CentralDockWidget);
    CentralDockArea->setAllowedAreas(DockWidgetArea::OuterDockAreas);

    // create other dock widgets
    QTreeView* fileTree = new QTreeView();
    fileTree->setFrameShape(QFrame::NoFrame);
    QFileSystemModel* fileModel = new QFileSystemModel(fileTree);
    fileModel->setRootPath(QDir::currentPath());
    fileTree->setModel(fileModel);
    CDockWidget* DataDockWidget = new CDockWidget("File system");
    DataDockWidget->setWidget(fileTree);
    DataDockWidget->resize(150, 250);
    DataDockWidget->setMinimumSize(100, 250);
    auto* fileArea = DockManager->addDockWidgetTabToArea(DataDockWidget, CentralDockArea); // CHANGED
    ui->menuView->addAction(DataDockWidget->toggleViewAction());

    QTableWidget* table = new QTableWidget();
    table->setColumnCount(3);
    table->setRowCount(10);
    CDockWidget* TableDockWidget = new CDockWidget("Table");
    TableDockWidget->setWidget(table);
    TableDockWidget->setMinimumSizeHintMode(CDockWidget::MinimumSizeHintFromDockWidget);
    TableDockWidget->resize(250, 150);
    TableDockWidget->setMinimumSize(200,150);
    DockManager->addDockWidgetTabToArea(TableDockWidget, CentralDockArea); // CHANGED
    ui->menuView->addAction(TableDockWidget->toggleViewAction());

    QTableWidget* propertiesTable = new QTableWidget();
    propertiesTable->setColumnCount(3);
    propertiesTable->setRowCount(10);
    CDockWidget* PropertiesDockWidget = new CDockWidget("Properties");
    PropertiesDockWidget->setWidget(propertiesTable);
    PropertiesDockWidget->setMinimumSizeHintMode(CDockWidget::MinimumSizeHintFromDockWidget);
    PropertiesDockWidget->resize(250, 150);
    PropertiesDockWidget->setMinimumSize(200,150);
    DockManager->addDockWidgetTabToArea(PropertiesDockWidget, CentralDockArea); // CHANGED
    ui->menuView->addAction(PropertiesDockWidget->toggleViewAction());

    createPerspectiveUi();
}

[githubuser0xFFFF]

Thank you for this fix.