Just hold down Ctrl button while scrolling with mouse wheel... I have tested this (non exhaustively) on Revit 2013 and Windows 7, and it works fine on the following dialogs:

  • the Properties Palette (wow!)
  • the data section of the Type Properties (Edit Type) dialog
  • Family Types
  • the Family Parameters part (lower section) of the Family Category and Parameters dialog
  • IFC Export and Import Options dialogs
  • Fill Patterns settings
  • Sheet Issues/Revisions

Thanks to this tweet for the heads-up:
@paulfaubin discovering #revit tricks! Ctrl+scroll on family type window to zoom in and out.
— Matias Cena (@onbeesknees) September 18, 2013

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