Steps to recreate:
[LIST=1]
[*]Click anywhere on the zplayer screen
[*]Cheat->Set Cheat
[*]Observe radio button 4 is already selected, without having entered a cheat code yet
[/LIST]
All cheat levels appear to be available because the radio buttons seem to retain their state when closing and reopening the window no matter which level is selected. Resetting the system resets the cheat level to 4.