API: Add gtk_widget_is_visible()

This is a recursive gtk_widget_get_visible(): Returns TRUE if the widget
and all its parents are visible.

docs/reference/gtk/gtk3-sections.txt

@@ -5291,6 +5291,7 @@ gtk_widget_get_sensitive
 gtk_widget_is_sensitive
 gtk_widget_get_state
 gtk_widget_get_visible
+gtk_widget_is_visible
 gtk_widget_set_visible
 gtk_widget_set_state_flags
 gtk_widget_unset_state_flags

gtk/gtk.symbols

@@ -3708,6 +3708,7 @@ gtk_widget_is_composited
 gtk_widget_is_drawable
 gtk_widget_is_focus
 gtk_widget_is_sensitive
+gtk_widget_is_visible
 gtk_widget_is_toplevel
 gtk_widget_keynav_failed
 gtk_widget_list_accel_closures

gtk/gtkwidget.c

@@ -7484,9 +7484,11 @@ _gtk_widget_set_visible_flag (GtkWidget *widget,
  * gtk_widget_get_visible:
  * @widget: a #GtkWidget
  *
- * Determines whether the widget is visible. Note that this doesn't
- * take into account whether the widget's parent is also visible
- * or the widget is obscured in any way.
+ * Determines whether the widget is visible. If you want to
+ * take into account whether the widget's parent is also marked as
+ * visible, use gtk_widget_is_visible() instead.
+ *
+ * This function does not check if the widget is obscured in any way.
  *
  * See gtk_widget_set_visible().
  *
@@ -7502,6 +7504,39 @@ gtk_widget_get_visible (GtkWidget *widget)
   return widget->priv->visible;
 }
 
+/**
+ * gtk_widget_is_visible:
+ * @widget: a #GtkWidget
+ *
+ * Determines whether the widget and all its parents are marked as
+ * visible.
+ *
+ * This function does not check if the widget is obscured in any way.
+ *
+ * See also gtk_widget_get_visible() and gtk_widget_set_visible()
+ *
+ * Return value: %TRUE if the widget and all its parents are visible
+ *
+ * Since: 3.8
+ **/
+gboolean
+gtk_widget_is_visible (GtkWidget *widget)
+{
+  g_return_val_if_fail (GTK_IS_WIDGET (widget), FALSE);
+
+  while (widget)
+    {
+      GtkWidgetPrivate *priv = widget->priv;
+
+      if (!priv->visible)
+        return FALSE;
+
+      widget = priv->parent;
+    }
+
+  return TRUE;
+}
+
 /**
  * gtk_widget_set_has_window:
  * @widget: a #GtkWidget

gtk/gtkwidget.h

@@ -589,6 +589,7 @@ gboolean              gtk_widget_is_sensitive           (GtkWidget    *widget);
 void                  gtk_widget_set_visible            (GtkWidget    *widget,
                                                          gboolean      visible);
 gboolean              gtk_widget_get_visible            (GtkWidget    *widget);
+gboolean              gtk_widget_is_visible             (GtkWidget    *widget);
 
 void                  gtk_widget_set_has_window         (GtkWidget    *widget,
                                                          gboolean      has_window);