For surface with parent backend should be fixed.

ui/gl/gl_detection.cpp

@@ -46,8 +46,13 @@ Capabilities CheckCapabilities(QWidget *widget) {
 	auto tester = QOpenGLWidget(widget);
 	tester.setFormat(format);
 	tester.grabFramebuffer(); // Force initialize().
+	if (!tester.window()->windowHandle()) {
+		tester.window()->createWinId();
+	}
 	const auto context = tester.context();
-	if (!context) {
+	if (!context
+		|| !context->isValid()
+		|| !context->makeCurrent(tester.window()->windowHandle())) {
 		LOG_ONCE(("OpenGL: Could not create widget in a window."));
 		return {};
 	}

ui/gl/gl_detection.h

@@ -10,6 +10,11 @@
 
 namespace Ui::GL {
 
+enum class Backend {
+	Raster,
+	OpenGL,
+};
+
 struct Capabilities {
 	bool supported = false;
 	bool transparency = false;

ui/gl/gl_surface.cpp

@@ -114,9 +114,24 @@ void Renderer::paint(
 }
 
 std::unique_ptr<RpWidgetWrap> CreateSurface(
-		QWidget *parent,
 		Fn<ChosenRenderer(Capabilities)> chooseRenderer) {
-	auto chosen = chooseRenderer(CheckCapabilities(parent));
+	auto chosen = chooseRenderer(CheckCapabilities(nullptr));
+	switch (chosen.backend) {
+	case Backend::OpenGL:
+		return std::make_unique<SurfaceOpenGL>(
+			nullptr,
+			std::move(chosen.renderer));
+	case Backend::Raster:
+		return std::make_unique<SurfaceRaster>(
+			nullptr,
+			std::move(chosen.renderer));
+	}
+	Unexpected("Backend value in Ui::GL::CreateSurface.");
+}
+
+std::unique_ptr<RpWidgetWrap> CreateSurface(
+		QWidget *parent,
+		ChosenRenderer chosen) {
 	switch (chosen.backend) {
 	case Backend::OpenGL:
 		return std::make_unique<SurfaceOpenGL>(

ui/gl/gl_surface.h

@@ -19,11 +19,6 @@ class RpWidgetWrap;
 
 namespace Ui::GL {
 
-enum class Backend {
-    OpenGL,
-    Raster,
-};
-
 class Renderer {
 public:
     virtual void init(
@@ -62,7 +57,10 @@ struct ChosenRenderer {
 };
 
 [[nodiscard]] std::unique_ptr<RpWidgetWrap> CreateSurface(
-    QWidget *parent,
     Fn<ChosenRenderer(Capabilities)> chooseRenderer);
 
+[[nodiscard]] std::unique_ptr<RpWidgetWrap> CreateSurface(
+	QWidget *parent,
+	ChosenRenderer chosen);
+
 } // namespace Ui::GL