[#73903866] Adjust dialog sizing and scrollbars.

@macumber 
@kbenne this was commented out in https://github.com/NREL/OpenStudio/commit/43e33be73ce7a9dc87b404bcbfaeb3a422036b13, presumably because it hides a method in the base class?  Do you remember the details?  @evanweaver maybe we could rename this something different?  PreferredSize or something?