button: Mention differentiating style classes

There's a lot of button variations out there, lets document
the ones we know about.

diff --git a/gtk/gtkbutton.c b/gtk/gtkbutton.c
index f976194caf7eaf156a038584628fd7681342575d..08c0dd31eae59578da82da2cf267f8ebb86dfeca 100644 (file)
--- a/gtk/gtkbutton.c
+++ b/gtk/gtkbutton.c
@@ -43,6 +43,11 @@
  *
  * Other style classes that are commonly used with GtkButton include
  * .suggested-action and .destructive-action.
+ *
+ * Button-like widgets like #GtkToggleButton, #GtkMenuButton, #GtkVolumeButton,
+ * #GtkLockButton, #GtkColorButton, #GtkFontButton or #GtkFileChooserButton use
+ * style classes such as .toggle, .popup, .scale, .lock, .color, .font, .file
+ * to differentiate themselves from a plain GtkButton.
  */
 
 #include "config.h"