Steam F12 screenshot problem in C3 games

F12 screenshot function of Steam.

After the game is released on Steam. Players press F12, the developer tool interface jump out directly, instead of screenshot. How can I create this screenshot function, it seems not make by C3 because all the game has the F12 screenshot function.

I don´t know how the screenshot function works with Steam and if you have to implement some code for it to work, but you can use this code snippet in a script file to disable such browser inputs.

> document.addEventListener('keydown', function(event) {
	event.preventDefault();
});

If you only want to prevent the F12 shortcut you can use this instead.

document.addEventListener('keydown', function(event) {
if(event.keyCode == 123) {
		event.preventDefault();
}
});

It's a great help! Thank you very much