I figured it out. In my call to create the DialogBox I put this: 
-showcommand  => sub { my($dlg) = @_; $dlg->geometry('900x600+400+250'
+); }

[download]
Just calling geometry() on creation was fine for the first time the dialog was posted, but if I close and then reopen the dialog, the coordinates revert to the bad location.

This approach to setting coordinates is about the most obscure one I have ever seen. - Paul

In reply to Re: How do I move a top level window in Tk? by paulchernoch
in thread How do I move a top level window in Tk? by paulchernoch

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