Use virtual function to retrieve interface pointer

xfa/fwl/lightwidget/cfwl_pushbutton.h

Index: xfa/fwl/lightwidget/cfwl_pushbutton.h
diff --git a/xfa/fwl/lightwidget/cfwl_pushbutton.h b/xfa/fwl/lightwidget/cfwl_pushbutton.h
index c2b71681c297cccbceeacea9771f1bd27d482dd9..ce26a54655c72e186d026ef55236269dd4f23ee2 100644
--- a/xfa/fwl/lightwidget/cfwl_pushbutton.h
+++ b/xfa/fwl/lightwidget/cfwl_pushbutton.h
@@ -15,6 +15,9 @@ class CFWL_PushButton : public CFWL_Widget {
   CFWL_PushButton();
   ~CFWL_PushButton() override;
 
+  IFWL_PushButton* GetWidget() override;
+  const IFWL_PushButton* GetWidget() const override;
+
   static CFWL_PushButton* Create();
 
   FWL_Error Initialize(const CFWL_WidgetProperties* pProperties = nullptr);