Good point.
I've yet to make this mistake, but I'm keenly aware to be careful when clicking for the next puzzle, to immediately move the cursor off the underlying Hint button.
However, I also see it as a good thing, as another pitfall of puzzledom, to trip up unwary laggards who should put more care into their efforts. All chess puzzles deserve respect and due diligence, and comeuppance is standard fare for those who care less.
Think of it as the 39th Definition and Example of Chess Tactics.
I agree with squaley. I've also inadvertently hit the button dozens of times as I study the puzzle & forget the mouse arrow is there. Avoiding this mistake is an unnecessary effort. Effort in solving the puzzle should be the only priority. At least add a "are you sure?" message or a setting to use that, if one wants it, as an option. Accidently brushing the very sensitive mouse pad with a thumb and activating the hint does not make one an unwary laggard nor does it show a lack of tactics. It's simply a programming oversight, a bug, and needs to be fixed. Thanks,
Adding a confirmation dialog to the hint button (or allowing that as a feature setting for puzzles) would be excellent as @yellowwood85 suggests. I too have inadvertently hit that button a few times -- before I trained myself to make sure my mouse was off the button. I like the delay that's built in to help avoid this - but allowing for a simple confirmation would be my preference.
Another thing is the opening move of the puzzle happens so fast that I have to use the "back" button (very close to the "hint" button) to go back and see which of my pieces was taken. I've probably clicked the hint button a few times doing this. It'd be nice to have a one or two second delay on the opening move or show the piece taken.
I've hit that button maybe 30 times, always by mistake, because it's right under the mouse after starting a puzzle. It ruins the puzzle.