An item used in a patch may sometimes be missing. Dead boxes refer to saved items that OM cannot find anymore :
Dead boxes have been designed to keep as much information as possible about their original reference, so that they can possibly be loaded again correctly.
If the user tries to open a dead box or to get information or documentation, the box doc will say "I have lost my reference, I am dead"...
... or a message of the same kind.
When a dead box "knows" which reference – class or function for instance – it was attached to, it can possibly be restored. Its reference must be loaded again or re-created before the patch is reloaded. To reload a patch containing dead boxes, use the "Last Saved" command.
If a patch reference is missing in the workspace, OM will point it out and offer to find it. If the item can't be found, the user will be offered to look for it by himself.