The bottom of the main window shows the total bytes in the project
along with how many are code, data, and junk. The junk figure wasn't
updating if you changed a data item to junk or vice-versa, because a
simple format change doesn't require reanalyzing the file.
To make the counter "live", we need to tell the updater to refresh the
values whenever a format changes to or from "junk".
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