With the Tk (and Python) that ship with Mountain Lion, preventing window resizing only works for both directions, if either with or height are true that call has no effect.
This seems to be a function of how Cocoa windows apply various window flags. The resizable attribute cannot be applied in one direction only; it seems, indeed, to be all or nothing. This is likely a documentation bug that should be addressed in the man pages.
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This seems to be a function of how Cocoa windows apply various window flags. The resizable attribute cannot be applied in one direction only; it seems, indeed, to be all or nothing. This is likely a documentation bug that should be addressed in the man pages.