The green bar that shows up when gathering

[LloydWaver]

I remember when I got that 'clam meat quest' and was harvesting clams and starfishes for the first time in the game. No need to say, I noticed the bar with a suspicious looking line in it. Well I thought I better click again if the bar reaches that line. I tried so and it didn't work. By that time my character already harvested the thing. I thought: "Must be a bug or not implented or whatever"

So yeah, after a long while I ask my friend about it and he says you need to click. Well now I'm clicking on every damn copper ore, but it just won't work. Well, I just want it to succeed once just to see for myself.