I do it like this, create a global variable call opacityToggle, it holds one of two values, it is either on or off (or maybe 1 or 0). On your grid button give it two frames of animation (set animation speed to 0). Everything then works off the variable. If oppacityToggle is "on" then set the animation frame for the button to on. If oppacityToggle is "off" set the Gridbutton animation frame to 2 (off). Make sure frame one is your On image of the button, and frame 2 is your off animation for the button (I am assuming here that the button is a sprite with the on touch/on click behavior). You then have an event that says if opacityToggle = "On" Set opacity to 100, Else Set opacity to 0 (or whatever it should be.
Basically you use the variable to track if the opacity is on or off and everything else uses that.