[gimp] app: call parent's window_state_event() from GimpImageWindow

[Jehan <jehanp src gnome org>]

commit 603c5dcb2cb6d75257ba4fcc337a1d5abd964c63
Author: Pavel Artsishevsky <polter rnd gmail com>
Date:   Mon May 17 19:20:47 2021 +0300

    app: call parent's window_state_event() from GimpImageWindow
    
    Fixes #6883

 app/display/gimpimagewindow.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/app/display/gimpimagewindow.c b/app/display/gimpimagewindow.c
index 8f0b3fc429..7a2e1c61ca 100644
--- a/app/display/gimpimagewindow.c
+++ b/app/display/gimpimagewindow.c
@@ -708,6 +708,10 @@ gimp_image_window_window_state_event (GtkWidget           *widget,
   GimpImageWindowPrivate *private = GIMP_IMAGE_WINDOW_GET_PRIVATE (window);
   GimpDisplayShell       *shell   = gimp_image_window_get_active_shell (window);
 
+  /* Run the parent implementation */
+  if (GTK_WIDGET_CLASS (parent_class)->window_state_event)
+    GTK_WIDGET_CLASS (parent_class)->window_state_event (widget, event);
+
   if (! shell)
     return FALSE;