I changed the title to generalize this issue.

The modal Options => Configure IDLE box does not have minimize or maximize buttons and cannot be resized.  (Ditto for About Idle.) This is typical of Windows dialogs, even though horizontal expansion would often be useful for path displays.  The modal Options => Configure Extensions box also does not have the button but *can* be resized. (Ditto for some other help displays.)

The Find, Find in Files, and Replace dialogs are also modal, though perhaps they should not be.  They have the buttons and can be maximized (which is useless).  They cannot be minimized because focus would have to shift to another window of the application, which would contradict being modal.  They can be resized, and this is occasionally needed and should stay.  One fix would be to make all these dialogs like Configure Extension -- no min, max buttons but resizable.

For reference, (but not part of this issue) the File menu dialogs that I checked are non-modal.  The Idle-specific Class and Path Browsers have min/max buttons and appear on the taskbar.  (Ditto for Debugger and IDLE Help.) The tk-defined Open and Save dialogs do not have the buttons and do not appear on the taskbar.  I believe the find group are the only modal dialogs with min and max buttons.