TODO:
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- Support for user-defined non-standard widgets.
  Users should be able to "register" their own widgets.
- Saving/Loading projects.
- Deleting/Closing projects.
- Dumping valid Perl code.
- Undo.
- ZooZ application icon.
- More standard widget icons.
- Support for special widgets like Notebooks/Scrollbars/Adjuster.
- Proper support for all widget configuration options like -command, -textvariable, etc ..
