Fix multiple bins should always stay tabbed together.

Related to #1290

src/layoutmanagement.cpp

@@ -215,6 +215,7 @@ bool LayoutManagement::loadLayout(const QString &layoutId, bool selectButton)
     }
     pCore->window()->centralWidget()->setHidden(!timelineVisible);
     pCore->window()->restoreState(state);
+    pCore->window()->tabifyBins();
     if (selectButton) {
         // Activate layout button
         QList<QAbstractButton *>buttons = m_containerGrp->buttons();

src/mainwindow.cpp

@@ -4607,6 +4607,16 @@ void MainWindow::addBin(Bin *bin, const QString &binName)
     m_binWidgets << bin;
 }
 
+void MainWindow::tabifyBins()
+{
+    QList<QDockWidget *> docks = findChildren<QDockWidget *>();
+    for (auto dock : qAsConst(docks)) {
+        if (dock->objectName().startsWith(QLatin1String("project_bin_"))) {
+            tabifyDockWidget(m_projectBinDock, dock);
+        }
+    }
+}
+
 Bin *MainWindow::getBin()
 {
     if (m_binWidgets.isEmpty()) {

src/mainwindow.h

@@ -140,6 +140,8 @@ public:
     Bin *getBin();
     /** @brief Get the active (focused) bin or first one if none is active*/
     Bin *activeBin();
+    /** @brief Ensure all bin widgets are tabbed together*/
+    void tabifyBins();
     int binCount() const;
 
     /** @brief Hide subtitle track */