docs: Add more detail to the drawing overview

diff --git a/docs/reference/gtk/drawing-model.xml b/docs/reference/gtk/drawing-model.xml
index 27cf247aefd71a46b4c28deb90ebf6e26804a551..88b10df78a7073c1700114f3fd078ef6fe49fc6c 100644 (file)
--- a/docs/reference/gtk/drawing-model.xml
+++ b/docs/reference/gtk/drawing-model.xml
@@ -206,11 +206,17 @@
         During the Paint phase GTK receives a single #GdkSurface::render signal on
         the toplevel surface. The signal handler will create a snapshot object
         (which is a helper for creating a scene graph) and call the
-        #GtkWidget::snapshot() vfunc, which will propagate down the widget hierarchy. 
+        #GtkWidget::snapshot() vfunc, which will propagate down the widget hierarchy.
         This lets each widget snapshot its content at the right place and time,
         correctly handling things like partial transparencies and overlapping widgets.
       </para>
 
+      <para>
+        During the snapshotting of each widget, GTK automatically handles the CSS
+        rendering according to the CSS box model. It snapshots first the background,
+        then the border, then the widget content itself, and finally the outline.
+      </para>
+
       <para>
         To avoid excessive work when generating scene graphs, GTK caches render nodes.
         Each widget keeps a reference to its render node (which in turn, will refer to