Glade-2 has "add eventbox" and "add alignment" for some widgets...

It would be nice to allow the user to add any container to the
selected widget (or remove the parenting container from the heirarchy
in a single click).

This would be a nice, slightly obscure power-user feature I think.

It would also be easily accomplished like this:

    o Mark widgets in the catalog to be put into the catagory
      of addable/removable containers (i.e. most container display
      widgets dont count).
    o From glade-popup.c, use command grouping to remove/add shuffle
      the hierarchy.

One problem on the remove side is... do we use glade_command_delete()
for widgets that share the same parent ? or do we disable the remove
parent feature for widgets that share thier parent with other project
widgets ?