                 updatePublisher();
                 updateWindowTitle(false);
             });
-            file.browseForOpen("Open Flump Configuration");
+            file.browseForOpen("Open Flump Configuration", [
+                new FileFilter("Flump config (*.json)", "*.json") ]);
         });
         fileMenuItem.submenu.addItemAt(new NativeMenuItem("Sep", /*separator=*/true), 2);
 

        });

        function updateWindowTitle (modified :Boolean) :void {
            var name :String = (_confFile != null) ? _confFile.name : "Untitled";
            if (modified) name += "*";
            _win.title = name;
        };

        function saveAs (..._) :void {
            var file :File = new File();
            file.addEventListener(Event.SELECT, function (..._) :void {
                // Ensure the filename ends with .json
                if (!StringUtil.endsWith(file.name.toLowerCase(), ".json")) {
                    file = file.parent.resolvePath(file.name + ".json");
                }

                _confFile = file;
                trace("Conf file is now " + _confFile.nativePath);
                _settings.data["CONF_FILE"] = _confFile.nativePath;
