I have thought about factoring out common test code into helper functions either within test_configdialog or in a new module. One example: simulate a click on a listbox, with common before and after code. Another: Testing the group of selection widgets on both theme and keys pages. (If I were not planning to replace this group, we could factor out a SelectionFrame and put an instance on each page.)
We might do some such refactoring after this, before HighPageTest. Keep notes on redundancies you notice that might be candidates.