allow configering the root name in the desktop renderer

packages/interpreter/src/interpreter.js

@@ -1,5 +1,5 @@
-export function main() {
-  let root = window.document.getElementById("main");
+export function main(rootname = "main") {
+  let root = window.document.getElementById(rootname);
   if (root != null) {
     window.interpreter = new Interpreter(root);
     window.ipc.postMessage(serializeIpcMessage("initialize"));