[gimp/gimp-2-10] app: add gimp_gtk_container_clear()

[Ell <ell src gnome org>]

commit fba9de69ee5ede4e491ecab8343dc1533f7dcda0
Author: Ell <ell_se yahoo com>
Date:   Mon Aug 20 14:14:26 2018 -0400

    app: add gimp_gtk_container_clear()
    
    ... which removes all non-internal children of a GtkContainer.
    
    (cherry picked from commit fd64aae47bc6a61ec49c571771b1dad587ba446a)

 app/widgets/gimpwidgets-utils.c | 15 +++++++++++++++
 app/widgets/gimpwidgets-utils.h |  2 ++
 2 files changed, 17 insertions(+)
---
diff --git a/app/widgets/gimpwidgets-utils.c b/app/widgets/gimpwidgets-utils.c
index a7e065a257..b7b6d296b6 100644
--- a/app/widgets/gimpwidgets-utils.c
+++ b/app/widgets/gimpwidgets-utils.c
@@ -1611,6 +1611,21 @@ gimp_widget_set_fully_opaque (GtkWidget *widget,
                             GINT_TO_POINTER (fully_opaque));
 }
 
+static void
+gimp_gtk_container_clear_callback (GtkWidget    *widget,
+                                   GtkContainer *container)
+{
+  gtk_container_remove (container, widget);
+}
+
+void
+gimp_gtk_container_clear (GtkContainer *container)
+{
+  gtk_container_foreach (container,
+                         (GtkCallback) gimp_gtk_container_clear_callback,
+                         container);
+}
+
 static gboolean
 gimp_print_event_free (gpointer data)
 {
diff --git a/app/widgets/gimpwidgets-utils.h b/app/widgets/gimpwidgets-utils.h
index 523bab1d0f..157d0d5ce4 100644
--- a/app/widgets/gimpwidgets-utils.h
+++ b/app/widgets/gimpwidgets-utils.h
@@ -112,6 +112,8 @@ gboolean          gimp_widget_get_fully_opaque     (GtkWidget            *widget
 void              gimp_widget_set_fully_opaque     (GtkWidget            *widget,
                                                     gboolean              fully_opaque);
 
+void              gimp_gtk_container_clear         (GtkContainer         *container);
+
 const gchar     * gimp_print_event                 (const GdkEvent       *event);
 
 gboolean          gimp_color_profile_store_add_defaults