tdf#124694 gtk3 GtkFixed takes the max size of all its children...

as its preferred size, causing it to not clip its child, but grow instead to
match

Change-Id: I57f740177aae619d11966f5382a6cc5f7a964be3
Reviewed-on: https://gerrit.libreoffice.org/73170
Tested-by: Jenkins
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>

vcl/unx/gtk3/gtk3gtkframe.cxx

@@ -913,11 +913,30 @@ void GtkSalFrame::resizeWindow( long nWidth, long nHeight )
         window_resize(nWidth, nHeight);
 }
 
+// tdf#124694 GtkFixed takes the max size of all its children as its
+// preferred size, causing it to not clip its child, but grow instead.
+
+static void
+ooo_fixed_get_preferred_height(GtkWidget*, gint *minimum, gint *natural)
+{
+    *minimum = 0;
+    *natural = 0;
+}
+
+static void
+ooo_fixed_get_preferred_width(GtkWidget*, gint *minimum, gint *natural)
+{
+    *minimum = 0;
+    *natural = 0;
+}
+
 static void
 ooo_fixed_class_init(GtkFixedClass *klass)
 {
     GtkWidgetClass *widget_class = GTK_WIDGET_CLASS(klass);
     widget_class->get_accessible = ooo_fixed_get_accessible;
+    widget_class->get_preferred_height = ooo_fixed_get_preferred_height;
+    widget_class->get_preferred_width = ooo_fixed_get_preferred_width;
 }
 
 /*