[gtk/menu-section-title-fixup] popovermenu: Don't put a separator before the first section

[Matthias Clasen <matthiasc src gnome org>]

commit a837b578495e242df60bdc20e9873789f7302834
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Apr 27 20:26:02 2020 -0400

    popovermenu: Don't put a separator before the first section
    
    When we have section titles, we were not hiding the
    separator before the first section as we should;
    fix this.
    
    Fixes: #2672

 gtk/gtkmenusectionbox.c | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/gtk/gtkmenusectionbox.c b/gtk/gtkmenusectionbox.c
index e6a55fae55..6a36ae7510 100644
--- a/gtk/gtkmenusectionbox.c
+++ b/gtk/gtkmenusectionbox.c
@@ -135,6 +135,13 @@ gtk_menu_section_box_sync_separators (GtkMenuSectionBox *box,
 
   gtk_widget_set_margin_top (GTK_WIDGET (box->item_box), should_have_top_margin ? 10 : 0);
 
+  if (has_label)
+    {
+      GtkWidget *separator = gtk_widget_get_first_child (box->separator);
+
+      gtk_widget_set_visible (separator, n_items_before > 0);
+    }
+
   if (should_have_separator == has_separator)
     return;