[gimp/gimp-2-10] Issue #2332 - Marching ants from one image displayed on every tab

[Michael Natterer <mitch src gnome org>]

commit 7dc96c8f3409895d0241b0ee1866fe0a83f47d38
Author: Michael Natterer <mitch gimp org>
Date:   Mon Oct 22 00:00:59 2018 +0200

    Issue #2332 - Marching ants from one image displayed on every tab
    
    Seems we were drawing marching ants for hidden tabs ever since the
    introduction of SWM, which is both a horrible waste of CPU time, and
    also makes all selections visible on all displays on GTK+ 3.x.
    
    Implement GtkWidget::unmap() in GimpDisplayShell and stop the ants
    when the shell is unmapped.
    
    (cherry picked from commit 1d43e2ff37b863de62b0382088b50f4ee974c31a)

 app/display/gimpdisplayshell.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)
---
diff --git a/app/display/gimpdisplayshell.c b/app/display/gimpdisplayshell.c
index 96d1d87325..559d01bea5 100644
--- a/app/display/gimpdisplayshell.c
+++ b/app/display/gimpdisplayshell.c
@@ -140,6 +140,7 @@ static void      gimp_display_shell_get_property   (GObject          *object,
                                                     GParamSpec       *pspec);
 
 static void      gimp_display_shell_unrealize      (GtkWidget        *widget);
+static void      gimp_display_shell_unmap          (GtkWidget        *widget);
 static void      gimp_display_shell_screen_changed (GtkWidget        *widget,
                                                     GdkScreen        *previous);
 static gboolean  gimp_display_shell_popup_menu     (GtkWidget        *widget);
@@ -244,6 +245,7 @@ gimp_display_shell_class_init (GimpDisplayShellClass *klass)
   object_class->get_property       = gimp_display_shell_get_property;
 
   widget_class->unrealize          = gimp_display_shell_unrealize;
+  widget_class->unmap              = gimp_display_shell_unmap;
   widget_class->screen_changed     = gimp_display_shell_screen_changed;
   widget_class->popup_menu         = gimp_display_shell_popup_menu;
 
@@ -978,6 +980,16 @@ gimp_display_shell_unrealize (GtkWidget *widget)
   GTK_WIDGET_CLASS (parent_class)->unrealize (widget);
 }
 
+static void
+gimp_display_shell_unmap (GtkWidget *widget)
+{
+  GimpDisplayShell *shell = GIMP_DISPLAY_SHELL (widget);
+
+  gimp_display_shell_selection_undraw (shell);
+
+  GTK_WIDGET_CLASS (parent_class)->unmap (widget);
+}
+
 static void
 gimp_display_shell_screen_changed (GtkWidget *widget,
                                    GdkScreen *previous)