I thought I read somewhere that there was a way to adjust the brush opacity interactively in CS6 (13) in the same way you adjust brush size and hardness (ie: Alt+Right-click and drag). In fact, the CS6 UI seems to support this, because it now shows a readout for Size, Hardness AND Opacity.
Of course, you can adjust brush opacity with the slider, and by typing the number directly on the keyboard, and in Prefs you can disable Hardness vertical HUD movement which then replaces it with Opacity.
But I want all three axes. Anyone know the trick? workaround? prayer?