qpa: Implement QPlatformWindow::requestActivateWindow()

src/plugins/qpa/window.cpp

@@ -54,6 +54,11 @@ QSurfaceFormat Window::format() const
     return m_format;
 }
 
+void Window::requestActivateWindow()
+{
+    QWindowSystemInterface::handleWindowActivated(window());
+}
+
 void Window::setGeometry(const QRect &rect)
 {
     const QRect &oldRect = geometry();

src/plugins/qpa/window.h

@@ -36,6 +36,7 @@ public:
     void setGeometry(const QRect &rect) override;
     WId winId() const override;
     qreal devicePixelRatio() const override;
+    void requestActivateWindow() override;
 
     void bindContentFBO();
     const QSharedPointer<QOpenGLFramebufferObject> &contentFBO() const;