diff --git a/toonz/sources/toonzqt/docklayout.h b/toonz/sources/toonzqt/docklayout.h
index b19472a..2b0a69f 100644
--- a/toonz/sources/toonzqt/docklayout.h
+++ b/toonz/sources/toonzqt/docklayout.h
@@ -163,7 +163,7 @@ private:
 
   \sa DockLayout and DockPlaceholder classes.
 */
-class DVAPI DockWidget : public QWidget {
+class DVAPI DockWidget : public QFrame {
   friend class DockLayout;  // DockLayout is granted access to placeholders'
                             // privates
   friend class DockPlaceholder;  // As above.
diff --git a/toonz/sources/toonzqt/dockwidget.cpp b/toonz/sources/toonzqt/dockwidget.cpp
index 44b58cf..bd513c2 100644
--- a/toonz/sources/toonzqt/dockwidget.cpp
+++ b/toonz/sources/toonzqt/dockwidget.cpp
@@ -105,7 +105,7 @@ inline void DockLayout::update() {
 //! (i.e. not docked
 //! into the layout).
 DockWidget::DockWidget(QWidget *parent, Qt::WindowFlags flags)
-    : QWidget(parent, flags)
+    : QFrame(parent, flags)
     , m_dragging(false)
     , m_resizing(false)
     , m_floating(true)