gtk2/docs/reference/gdk/gdk-overrides.txt

# GdkPixmap, GdkBitmap and GdkDrawable are the same as GdkWindow.
<STRUCT>
<NAME>GdkWindow</NAME>
struct GdkPixmap
{
  gpointer user_data;
};
</STRUCT>
<STRUCT>
<NAME>GdkPixmap</NAME>
struct GdkPixmap
{
  gpointer user_data;
};
</STRUCT>
<STRUCT>
<NAME>GdkDrawable</NAME>
struct GdkDrawable
{
  gpointer user_data;
};
</STRUCT>

# GdkAtom is an opaque typedef
<STRUCT>
<NAME>GdkAtom</NAME>
</STRUCT>

<MACRO>
<NAME>GDK_WINDOWING_X11</NAME>
#define GDK_WINDOWING_X11
</MACRO>

<MACRO>
<NAME>GDK_WINDOWING_WIN32</NAME>
#define GDK_WINDOWING_WIN32
</MACRO>

<MACRO>
<NAME>GDK_WINDOWING_FB</NAME>
#define GDK_WINDOWING_FB
</MACRO>