lokdialog: gtv: Set dialog title on callback

Change-Id: I6d96a9e2287afdcaad2f770e4b4c73d3671fc76b
(cherry picked from commit f0a6fd58575ff6b9ebbfb0835aa8694923ddbffd)

libreofficekit/qa/gtktiledviewer/gtv-lokdocview-signal-handlers.cxx

@@ -387,6 +387,11 @@ void LOKDocViewSigHandlers::window(LOKDocView* pDocView, gchar* pPayload, gpoint
 
                 gtv_lok_dialog_invalidate(GTV_LOK_DIALOG(pDialog), aGdkRectangle);
             }
+            else if (aAction == "title_changed")
+            {
+                const std::string aTitle = aRoot.get<std::string>("title", "");
+                gtk_window_set_title(pDialog, aTitle.c_str());
+            }
         }
     }
 }