src/ui/FrameTitleBar.cpp

@@ -186,3 +186,9 @@ void FrameTitleBar::SetSysButton(unsigned int sysBtn) {
     ui->sys_max->setVisible(static_cast<bool>(ftbButton_ & FTB_MAX));
     ui->sys_close->setVisible(static_cast<bool>(ftbButton_ & FTB_CLOSE));
 }
+
+
+void FrameTitleBar::showEvent(QShowEvent * event)
+{
+	OnMaxBtnClicked();
+}

src/ui/FrameTitleBar.h

@@ -46,6 +46,8 @@ protected:
     void mouseMoveEvent(QMouseEvent* event) override;
     void mouseDoubleClickEvent(QMouseEvent* event) override;
 
+	virtual void showEvent(QShowEvent *event) override;
+
 protected:
     void OnMinBtnClicked();
     void OnMaxBtnClicked();

src/ui/FramelessDelegateWin.cpp

@@ -128,7 +128,7 @@ bool FramelessDelegateWin::nativeEvent(const QByteArray & eventType, void* messa
                 }
             }
         }
-        *result = msg->wParam ? 0 : WVR_REDRAW;
+        *result = !msg->wParam ? 0 : WVR_REDRAW;
         return true;
     }
     case WM_NCPAINT: {

src/viewer/OsgWidget.h

@@ -11,7 +11,6 @@ class OsgWidget :  public QWidget, public osgViewer::CompositeViewer {
 public:
     OsgWidget(QWidget *parent = nullptr, Qt::WindowFlags f = nullptr);
 	~OsgWidget() override;
-    QPaintEngine* paintEngine() const override { return nullptr; }
 
     void Initialize(void);
 	void Uninitialize(void);