[issue30853] IDLE: configdialog -- factor out VarTrace class

[Terry J. Reedy]

Changes by Terry J. Reedy <tjreedy at udel.edu>:


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title: IDLE: configdialog -- factor out Tracer subclass -> IDLE: configdialog -- factor out VarTrace class

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue30853>
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