Keeping some code closed every time i open a project

My question is really simple. I am working on a project and every time some code that i dont want to work on i whip it up by pressing the minus ( - ) sign and then i can only see the declaration of the method or sub or function. The problem is that even if i save the project the next time the code is again viewable and have to minimize it again. Any idea where i can find the option to change that cause i have seen that it stays "closed" in othe rcomputers.