docs: Strictify the docs for gtk_cairo_should_draw_window()

We don't actually enforce the docs, but we will in the future. (in fact,
I only added this because widgets were doing stupid things.)

diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 98f95289b2cd65f4ba6bbfd3c90f7b2728907f88..7dddae7dea2b86971b3074c8619e05a69f5c07da 100644 (file)
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -5628,7 +5628,8 @@ gtk_cairo_set_event (cairo_t        *cr,
 /**
  * gtk_cairo_should_draw_window:
  * @cr: a cairo context
- * @window: the window to check
+ * @window: the window to check. @window may not be an input-only
+ *          window.
  *
  * This function is supposed to be called in #GtkWidget::draw
  * implementations for widgets that support multiple windows.