I recently wrote about the perils my dev team encountered while working to build an editable grid in XUL. We came up with what seems to be a workable solution. Only after we did a lot of work to come up with this solution did I happen upon a bug report that pointed over to an editable tree example that does more or less what we were shooting for to begin with.
The main problems with our implementation are that it’s less scalable the more data you get (I’m not sure how scalable the tree example will be — haven’t tested it yet) and that it doesn’t have sortable, hideable, draggable columns by default, as a tree would. This is definitely a widget I’ll be looking into.
In other semi-related news, I found in the same bug report a link to a nifty date picker written in XUL. That too could come in handy.