[plt-dev] embedded gui inside hierlist

Embedded editor-snip's act strangely when put inside the text part of a 
hierarchical-list-item%. The editor-snip% doesn't get aligned properly 
so all its internal snips are bunched up in the left hand corner. The 
issue seems to be whether or not the content-snip of 
hierarchical-list-snip% is visible or not when the list is created. That 
is, I added the content-snip to the main buffer in the constructor of 
the hierarchical-list-snip% to fix the layout problems.

(sequence
   ...
   (send main-buffer insert content-snip 4)
   ....)

I'm not sure what the difference is between adding the content-snip to 
the main-buffer immediately and when doing it in the handle-open call, 
but hopefully someone else has a better idea.

What I'm trying to do is something like this:
  (let ([item (send list new-list)]
         [my-editor (new pasteboard%)]
     (send (send item get-editor) insert (new editor-snip% [editor 
my-editor]))
     (send my-editor insert ...stuff...))