[meld] bin/meld: Update requirements dialog to remove deprecated initialisation

[Kai Willadsen <kaiw src gnome org>]

commit 675b9f0c820b7900d03900e06c3825fbbb443015
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Fri Jul 5 11:31:16 2019 +1000

    bin/meld: Update requirements dialog to remove deprecated initialisation
    
    This also changes it so that we don't have a top-level window, just the
    dialog.

 bin/meld | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/bin/meld b/bin/meld
old mode 100755
new mode 100644
index e2ff50e7..83d11248
--- a/bin/meld
+++ b/bin/meld
@@ -154,11 +154,11 @@ def show_error_and_exit(error_text):
         import gi
         gi.require_version("Gtk", "3.0")
         from gi.repository import Gtk
-        toplevel = Gtk.Window(title="Meld")
-        toplevel.show()
         Gtk.MessageDialog(
-            toplevel, 0, Gtk.MessageType.ERROR,
-            Gtk.ButtonsType.CLOSE, error_text).run()
+            message_type=Gtk.MessageType.ERROR,
+            buttons=Gtk.ButtonsType.CLOSE,
+            text=error_text,
+        ).run()
     except Exception:
         # Although tkinter is imported here, it isn't meld's dependency:
         # if found it is used to show GUI error about lacking true dependecies.