added about dialog to app

src/main.rs

@@ -56,6 +56,7 @@ fn build_ui(app: &Application) {
     
     // set popover_menu methods
     popover_menu.set_texts();
+    popover_menu.click_about_button();
 
     // TODO: Set popover textviews and put them in a separate file
     // set header bar methods