[gtk+] popover: Fix a warning

[Matthias Clasen <matthiasc src gnome org>]

commit af5d3e3299eac52ba14fe90232cff385e66176b5
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Sep 6 08:04:33 2017 -0400

    popover: Fix a warning
    
    We were unintentionally disconnecting an already-disconnected
    signal handler in some cases. Don't do that, it causes warnings.

 gtk/gtkpopover.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkpopover.c b/gtk/gtkpopover.c
index 5bc10c8..8bde783 100644
--- a/gtk/gtkpopover.c
+++ b/gtk/gtkpopover.c
@@ -621,6 +621,8 @@ gtk_popover_apply_modality (GtkPopover *popover,
   else
     {
       g_signal_handlers_disconnect_by_data (priv->window, popover);
+      if (priv->prev_focus_widget == GTK_WIDGET (priv->window))
+        priv->prev_focus_unmap_id = 0;
       gtk_grab_remove (GTK_WIDGET (popover));
 
       /* Let prev_focus_widget regain focus */