Here's a little example on how to cycle through different pictos when pressing a button.
1. Go to 'Main Menu / Values'
2. Add value with id 'nine_traffic' and name 'nine_traffic' and default value 0, this will be our counter
4. Create a new button on a page, we'll attach a little program to this button which will increase the counter on every press, and then change the looks of the button depending on that value