Best example is clicking on the Hide/Show icon for blocks. When I do this I get a "el has no properties" for this line:

while(el.nodeName != 'BODY') {

This is in the findParentNode() method in the lib/javascript-static.js file.

I found that the el.nodeName returns the node name in lower case instead of all caps. I made a quick fix for this for the findParentNode() (see attached), but perhaps more investigations are needed for a more permanent and long term solution (EG: what other browsers return for .nodeName and other code that needs to be updated, etc).