diff --git a/src/private/Frame.cpp b/src/private/Frame.cpp
index e4a02742..8f0a9b8a 100644
--- a/src/private/Frame.cpp
+++ b/src/private/Frame.cpp
@@ -406,6 +406,7 @@ void Frame::setDropArea(DropArea *dt)
 {
     if (dt != m_dropArea) {
         qCDebug(docking) << "Frame::setDropArea dt=" << dt;
+        const bool wasInMainWindow = isInMainWindow();
         if (m_dropArea)
             disconnect(m_dropArea->multiSplitterLayout(), &MultiSplitterLayout::visibleWidgetCountChanged,
                        this, &Frame::updateTitleBarVisibility);
@@ -417,6 +418,9 @@ void Frame::setDropArea(DropArea *dt)
                     this, &Frame::updateTitleBarVisibility);
             updateTitleBarVisibility();
         }
+
+        if (wasInMainWindow != isInMainWindow())
+            Q_EMIT isInMainWindowChanged();
     }
 }
 
diff --git a/src/private/Frame_p.h b/src/private/Frame_p.h
index 56834c69..1c1f097b 100644
--- a/src/private/Frame_p.h
+++ b/src/private/Frame_p.h
@@ -207,6 +207,7 @@ Q_SIGNALS:
     void numDockWidgetsChanged();
     void hasTabsVisibleChanged();
     void layoutInvalidated();
+    void isInMainWindowChanged();
 
 private:
     Q_DISABLE_COPY(Frame)