Allow querying manual rounding radius of RpWindow.

ui/platform/ui_platform_window.cpp

@@ -188,6 +188,10 @@ void BasicWindowHelper::close() {
 	_window->close();
 }
 
+int BasicWindowHelper::manualRoundingRadius() const {
+	return 0;
+}
+
 void BasicWindowHelper::setBodyTitleArea(
 		Fn<WindowTitleHitTestFlags(QPoint)> testMethod) {
 	Expects(!_bodyTitleAreaTestMethod || testMethod);
@@ -524,6 +528,10 @@ void DefaultWindowHelper::setGeometry(QRect rect) {
 	window()->setGeometry(rect.marginsAdded(bodyPadding()));
 }
 
+int DefaultWindowHelper::manualRoundingRadius() const {
+	return _roundingOverlay ? Radius() : 0;
+}
+
 void DefaultWindowHelper::paintBorders(QPainter &p) {
 	const auto titleBackground = window()->isActiveWindow()
 		? _title->st()->bgActive

ui/platform/ui_platform_window.h

@@ -59,6 +59,7 @@ public:
 	virtual void showNormal();
 	virtual void close();
 
+	virtual int manualRoundingRadius() const;
 	void setBodyTitleArea(Fn<WindowTitleHitTestFlags(QPoint)> testMethod);
 
 protected:
@@ -91,6 +92,7 @@ public:
 	void setMinimumSize(QSize size) override;
 	void setFixedSize(QSize size) override;
 	void setGeometry(QRect rect) override;
+	int manualRoundingRadius() const override;
 
 protected:
 	bool eventFilter(QObject *obj, QEvent *e) override;

ui/widgets/rp_window.cpp

@@ -99,4 +99,8 @@ void RpWindow::setBodyTitleArea(
 	_helper->setBodyTitleArea(std::move(testMethod));
 }
 
+int RpWindow::manualRoundingRadius() const {
+	return _helper->manualRoundingRadius();
+}
+
 } // namespace Ui

ui/widgets/rp_window.h

@@ -65,6 +65,7 @@ public:
 	void showFullScreen();
 	void showNormal();
 	void close();
+	[[nodiscard]] int manualRoundingRadius() const;
 	void setBodyTitleArea(Fn<WindowTitleHitTestFlags(QPoint)> testMethod);
 
 private: