[latexila] MainWindowStructure: don't use gtk_menu_popup() (deprecated)

[Sébastien Wilmet <swilmet src gnome org>]

commit 2a1db380def2e2078a89652dd74f69ddc786bc5a
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Thu Dec 14 15:45:49 2017 +0100

    MainWindowStructure: don't use gtk_menu_popup() (deprecated)

 src/main_window_structure.vala |    6 +-----
 1 files changed, 1 insertions(+), 5 deletions(-)
---
diff --git a/src/main_window_structure.vala b/src/main_window_structure.vala
index 5e57584..148f94a 100644
--- a/src/main_window_structure.vala
+++ b/src/main_window_structure.vala
@@ -96,11 +96,7 @@ public class MainWindowStructure
     private void show_popup_menu (Gdk.EventButton? event)
     {
         Gtk.Menu popup_menu = _ui_manager.get_widget ("/StructurePopup") as Gtk.Menu;
-
-        if (event != null)
-            popup_menu.popup (null, null, null, event.button, event.time);
-        else
-            popup_menu.popup (null, null, null, 0, get_current_event_time ());
+        popup_menu.popup_at_pointer (event);
     }
 
     private void set_menu_insensitive ()