[gimp] Issue #3560: "Screenshot delay: __ seconds" item lacks mnemonic.

[Jehan <jehanp src gnome org>]

commit 3604e8e7adcc327dd35f95463909ec0cd85147bb
Author: Jehan <jehan girinstud io>
Date:   Mon Jun 24 12:00:51 2019 +0200

    Issue #3560: "Screenshot delay: __ seconds" item lacks mnemonic.

 plug-ins/screenshot/screenshot.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/plug-ins/screenshot/screenshot.c b/plug-ins/screenshot/screenshot.c
index 99c1e287e0..ca2731f65e 100644
--- a/plug-ins/screenshot/screenshot.c
+++ b/plug-ins/screenshot/screenshot.c
@@ -748,7 +748,7 @@ shoot_dialog (GdkMonitor **monitor)
       gtk_widget_show (grid);
     }
 
-  label = gtk_label_new (_("Screenshot delay: "));
+  label = gtk_label_new_with_mnemonic (_("Screenshot dela_y: "));
   gtk_grid_attach (GTK_GRID (grid), label, 0, 0, 1, 1);
   gtk_widget_show (label);
 
@@ -757,6 +757,7 @@ shoot_dialog (GdkMonitor **monitor)
   spinner = gimp_spin_button_new (adj, 0, 0);
   gtk_spin_button_set_numeric (GTK_SPIN_BUTTON (spinner), TRUE);
   gtk_grid_attach (GTK_GRID (grid), spinner, 1, 0, 1, 1);
+  gtk_label_set_mnemonic_widget (GTK_LABEL (label), GTK_WIDGET (spinner));
   gtk_widget_show (spinner);
 
   g_signal_connect (adj, "value-changed",