extern QGLWidget *global_share_widget;
QSurface *create_surface(const QSurfaceFormat &format);
+QSurface *create_surface_with_same_format(const QSurface *surface);
QOpenGLContext *create_context(const QSurface *surface);
bool make_current(QOpenGLContext *context, QSurface *surface);
+void delete_context(QOpenGLContext *context);