WebUI optimization (thx to @mkcologne)

Start Grabber only when global settings are enabled
Fixed an issue in the WebUI preview

assets/webconfig/js/ledsim.js

@@ -112,6 +112,7 @@ $(document).ready(function () {
       },
       closed: function (e) {
         modalOpened = false;
+        lC = false;
       },
       resizeStop: function (e) {
         setStorage("ledsim_width", $("#ledsim_dialog").outerWidth());