gtk; Deprecate gtk_render_frame_gap()

Use gtk_render_frame() instead.

gtk/gtkrender.c

@@ -757,6 +757,9 @@ gtk_css_style_render_frame_gap (GtkCssStyle     *style,
  * ![](frame-gap.png)
  *
  * Since: 3.0
+ *
+ * Deprecated: 3.24: Use gtk_render_frame() instead. Themes can create gaps
+ *     by omitting borders via CSS.
  **/
 void
 gtk_render_frame_gap (GtkStyleContext *context,

gtk/gtkrender.h

@@ -110,7 +110,7 @@ void        gtk_render_slider      (GtkStyleContext     *context,
                                     gdouble              width,
                                     gdouble              height,
                                     GtkOrientation       orientation);
-GDK_AVAILABLE_IN_ALL
+GDK_DEPRECATED_IN_3_24_FOR(gtk_render_frame)
 void        gtk_render_frame_gap   (GtkStyleContext     *context,
                                     cairo_t             *cr,
                                     gdouble              x,