paint_widget(math_view);
gtk_math_view_paint(math_view);
vadjustment_value_changed(GtkAdjustment* adj, GtkMathView* math_view){  g_return_if_fail(adj != NULL);  g_return_if_fail(math_view != NULL);  if (adj->value > adj->upper - adj->page_size) adj->value = adj->upper - adj->page_size;  if (adj->value < adj->lower) adj->value = adj->lower;  math_view->old_top_y = math_view->top_y;  math_view->top_y = static_cast<int>(adj->value);  if (math_view->old_top_y != math_view->top_y)    paint_widget(math_view);}