Fix affinity of central frame

Fixes issue #245

(cherry-picked from commit f9e758d02f)

src/private/DropAreaWithCentralFrame_p.h

@@ -29,6 +29,7 @@ public:
 private:
     friend class MainWindowBase;
     friend class Frame;
+    friend class ::TestDocks;
     Frame *const m_centralFrame = nullptr;
 };
 

src/private/Frame.cpp

@@ -588,6 +588,8 @@ bool Frame::hasTabsVisible() const
 QStringList Frame::affinities() const
 {
     if (isEmpty()) {
+        if (auto m = mainWindow())
+            return m->affinities();
         return {};
     } else {
         return dockWidgetAt(0)->affinities();

tests/tst_docks.cpp

@@ -17,6 +17,7 @@
 #include "DockWidgetBase.h"
 #include "DockWidgetBase_p.h"
 #include "DropAreaWithCentralFrame_p.h"
+#include "Frame_p.h"
 #include "LayoutSaver_p.h"
 #include "MDILayoutWidget_p.h"
 #include "MainWindowMDI.h"
@@ -7820,23 +7821,14 @@ void TestDocks::tst_closeTabOfCentralFrame()
     QVERIFY(frame->QWidgetAdapter::isVisible());
 }
 
-void TestDocks::tst_centralFrame245()
+void TestDocks::tst_centralGroupAffinity()
 {
-    /*
-
-    Build: -DKDDockWidgets_DEVELOPER_MODE=ON
-    Run: ./bin/tst_docks tst_centralFrame245 -platform xcb
-
     auto m = createMainWindow(QSize(500, 500), MainWindowOption_HasCentralFrame, "tst_centralFrame245");
-    auto dock1 = createDockWidget("1", new QPushButton("1"));
-    auto dock2 = createDockWidget("2", new QPushButton("2"));
+    const QStringList affinities = { "a" };
+    m->setAffinities(affinities);
 
-    m->addDockWidgetAsTab(dock1);
-    m->addDockWidgetAsTab(dock2);
-
-    QTest::qWait(100000);
-
-*/
+    Frame *centralGroup = m->dropArea()->m_centralFrame;
+    QCOMPARE(centralGroup->affinities(), affinities);
 }
 
 void TestDocks::tst_persistentCentralWidget()

tests/tst_docks.h

@@ -152,7 +152,7 @@ private Q_SLOTS:
     void tst_availableLengthForOrientation();
     void tst_closeShowWhenNoCentralFrame();
     void tst_closeTabOfCentralFrame();
-    void tst_centralFrame245();
+    void tst_centralGroupAffinity();
     void tst_setAsCurrentTab();
     void tst_placeholderDisappearsOnReadd();
     void tst_placeholdersAreRemovedProperly();