[gtk/popup-shadow-width] window: Add some more details to css docs

[Matthias Clasen <matthiasc src gnome org>]

commit 52a2891933907b9b9e5d718bb6faa69b6aa3d96c
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Feb 14 11:22:44 2021 -0500

    window: Add some more details to css docs
    
    Mention more of the supported style classes.

 gtk/gtkwindow.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index ac7f050738..b4de2cc97c 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -114,7 +114,7 @@
  * # CSS nodes
  *
  * |[<!-- language="plain" -->
- * window.background
+ * window.background [.csd / .solid-csd / .ssd] [.maximized / .fullscreen / .tiled]
  * ├── <child>
  * ╰── <titlebar child>.titlebar [.default-decoration]
  * ]|
@@ -125,9 +125,11 @@
  * client-side decorations are in use), .solid-csd (for client-side decorations
  * without invisible borders), .ssd (used by mutter when rendering server-side
  * decorations). GtkWindow also represents window states with the following
- * style classes on the main node: .tiled, .maximized, .fullscreen. Specialized
- * types of window often add their own discriminating style classes, such as
- * .popup or .tooltip.
+ * style classes on the main node: .maximized, .fullscreen, .tiled (when supported,
+ * also .tiled-top, .tiled-left, .tiled-right, .tiled-bottom).
+ *
+ * GtkWindow subclasses often add their own discriminating style classes,
+ * such as .dialog, .popup or .tooltip.
  *
  * Generally, some CSS properties don't make sense on the toplevel window node,
  * such as margins or padding. When client-side decorations without invisible