fix showing FileTransferChooser dialog

src/dialogs.py

@@ -1478,8 +1478,8 @@ class FileChooserDialog(Gtk.FileChooserDialog):
     select_multiple=False, current_folder=None, on_response_ok=None,
     on_response_cancel=None, transient_for=None):
 
-        GObject.GObject.__init__(self, title=title_text, parent=transient_for,
-            action=action)
+        Gtk.FileChooserDialog.__init__(self, title=title_text,
+            parent=transient_for, action=action)
         self.add_button(buttons[0],buttons[1])
         if len(buttons) ==4:
             self.add_button(buttons[2],buttons[3])

src/filetransfers_window.py

@@ -316,7 +316,8 @@ class FileTransfersWindow:
                 True, # select multiple true as we can select many files to send
                 gajim.config.get('last_send_dir'),
                 on_response_ok=on_ok,
-                on_response_cancel=lambda e:dialog.destroy()
+                on_response_cancel=lambda e:dialog.destroy(),
+                transient_for=gajim.interface.roster.window
                 )
 
         btn = Gtk.Button.new_with_mnemonic(_('_Send'))