avoid GTK3 warning

gui-lib/mred/private/wx/gtk/frame.rkt

@@ -245,7 +245,8 @@
     (define/override (set-child-size child-gtk x y w h)
       (gtk_fixed_move panel-gtk child-gtk (->screen x) (->screen y))
       ;; gtk3: we expect a panel in a frame to be always visible, so
-      ;; this size erquest should work
+      ;; this size request should work
+      (avoid-preferred-size-warning child-gtk)
       (gtk_widget_set_size_request child-gtk (->screen w) (->screen h)))
 
     (define/public (on-close) #t)

gui-lib/mred/private/wx/gtk/panel.rkt

@@ -144,6 +144,7 @@
 	     (begin
 	       (gtk_widget_show child-gtk)
 	       #t)))
+      (avoid-preferred-size-warning child-gtk)
       (gtk_widget_set_size_request child-gtk (->screen w) (->screen h))
       (when re-hide?
 	(gtk_widget_hide child-gtk)))))

gui-lib/mred/private/wx/gtk/window.rkt

@@ -55,6 +55,8 @@
               widget-allocation
               widget-parent
 
+	      avoid-preferred-size-warning
+
               the-accelerator-group
               gtk_window_add_accel_group
               gtk_menu_set_accel_group
@@ -102,6 +104,14 @@
 (define-gtk gtk_widget_get_scale_factor (_fun _GtkWidget -> _int)
   #:fail (lambda () (lambda (gtk) 1)))
 
+(define (avoid-preferred-size-warning gtk)
+  ;; If we don't ask for a widget's size in the right way,
+  ;; GTK3 may report a warning; this query avoids the
+  ;; warning.
+  (when gtk3?
+    (define req (make-GtkRequisition 0 0))
+    (gtk_widget_get_preferred_size gtk req #f)))
+
 (define-gdk gdk_keyboard_grab (_fun _GdkWindow _gboolean _int -> _void))
 (define-gdk gdk_keyboard_ungrab (_fun _int -> _void))