Thank you very much Yathosho it helped me very much.
But i still got another question and i dont know i its worth to open a new topic about it so ill ask it here.
When you look at attached the image, you will see a custom dialog. I made it and i want to have some things i could not find.
I want that users can choose between 2 checkboxes (Red, Green). So if they choose Green they cant choose Red.
I hope somebody can tell me how to do this.
And a second thing is how to automaticly check checkboxes and radiobuttons. (Blue area)
I hope somebody knows how to do this. It may have been somewhere on the NSIS pages but i didnt find it.