[gtk/about-dialog-icon-size: 4/7] aboutdialog: Set a style class

[Matthias Clasen <matthiasc src gnome org>]

commit 1d40750a6045c2c03250d5594e30ef3773c9c32a
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jan 11 16:48:06 2021 -0500

    aboutdialog: Set a style class
    
    Add the .aboutdialog style class to toplevel
    widget of about dialogs, similar to what we
    do for e.g. GtkAssistant.

 gtk/gtkaboutdialog.c     | 6 ++++++
 gtk/ui/gtkaboutdialog.ui | 3 +++
 2 files changed, 9 insertions(+)
---
diff --git a/gtk/gtkaboutdialog.c b/gtk/gtkaboutdialog.c
index bff8e76432..4cdee36575 100644
--- a/gtk/gtkaboutdialog.c
+++ b/gtk/gtkaboutdialog.c
@@ -101,6 +101,12 @@
  *                        "title", _("About ExampleCode"),
  *                        NULL);
  * ]|
+ *
+ * # CSS nodes
+ *
+ * GtkAboutDialog has a single CSS node with the name window and style
+ * class .aboutdialog.
+
  */
 
 typedef struct
diff --git a/gtk/ui/gtkaboutdialog.ui b/gtk/ui/gtkaboutdialog.ui
index ab5fe44b32..bd69376d6a 100644
--- a/gtk/ui/gtkaboutdialog.ui
+++ b/gtk/ui/gtkaboutdialog.ui
@@ -2,6 +2,9 @@
 <interface domain="gtk40">
   <template class="GtkAboutDialog" parent="GtkWindow">
     <property name="resizable">0</property>
+    <style>
+      <class name="aboutdialog"/>
+    </style>
     <child type="titlebar">
       <object class="GtkHeaderBar" id="headerbar1">
         <child type="title">