checkbox dojo doesn't get gray when set disabled

Every time user click one of the checkbox, it will autimatically check other ones, and if they meet the condition, they would be set disabled. However, I found that the checkbox can't get gray immediately——they only get gray when I click them, then I know they are disabled. But the purpose of doing this is to let users know which checkbox could be click or not.

So how could I make them get gray at once?