With the brush activated, the I and O keys increase and decrease the opacity, respectively, by 10%. Suppose I have a medium blue shade (#00b7d9)…
• If I press the I key once, the color goes from 100% opacity to 90%; if I press twice in a row, the opacity drops to 80%;
• If the color is at opacity, say, 50% and I press the O key once, it will go to 60%; if I press twice in a row, it goes to 70%;