Please make that right clicking on spinners in Corona materials and maps, would reset to their default values and not to the lowest possible ones. I know, that Ondra once said that it's 3ds max's limitation and i know that standart and Mental Ray materials acts the same, but... open any Vray material or map and right click on any of their spinners - they works as you'd expect! Somehow they've managed to hack the system. Now, that you belong to the same group and probably have the keys to their office, please go there at night and steel the code so we can finally can have that funcionality in Corona :]