fixed vivide and example for file tree widget

SQUASHED: AUTO-COMMIT-src-client-vivide-components-vivide-step-editor.js,AUTO-COMMIT-src-client-vivide-scripts-applications-vivide-lively-file-tree.json,AUTO-COMMIT-src-components-halo-lively-halo-vivide-script-suggestion.html,

src/client/vivide/components/vivide-step-editor.js

@@ -115,7 +115,7 @@ export default class VivideStepEditor extends Morph {
    * Generic path utilities
    */
   ast() {
-
+    const src = this.editor.value;
     return parseForAST(src).ast;
   }
 

src/components/halo/lively-halo-vivide-script-suggestion.html

@@ -14,9 +14,15 @@
   }
 
   #rel-container {
+    display: none;
+    visibility: hidden;
     box-sizing: border-box;
     position: relative;
   }
+  :host(:hover) #rel-container, :host(:focus-within) #rel-container {
+    display: block;
+    visibility: visible;
+  }
   #container {
     position: absolute;
     top: 30px;