Go to <http://webkit.org/> and open the inspector and double click the <body> node then double click the <div id="icon"> node. The body will successfully become the root object of the tree, but when you do the same for the #icon div, the following JS error is thrown in the console:
.../WebCore.framework/Resources/inspector/ElementsTreeOutline.js:491: JS ERROR: TypeError: Result of expression 'this.treeOutline' [null] is not an object.
The original problem is no longer repeatable. However, following is also a bug:
1) Open inspector using Inspect Element on the "Welcome" topic (important)
2) Double click on body
3) Double click on #icon div
Expected: Contents of body to be displayed
Actual: Contents of the welcome topic is displayed
The problem is that dblclick is being dispatched twice - via explicit listener and via tree element callback. Will issue a patch shortly.
Created attachment 39846 [details]
Committing to http://svn.webkit.org/repository/webkit/trunk ...