thanks for mentioning that! I will try to reproduce. Can you tell me which version of plasma and NK app you are using. You may even provide information about your OS?
I will first try on OpenSuse with plasma as I have it at hand. I came back as soon as possible, but probably it will be not before next week, I am sorry.
PS: I do not see a security issue for now, but it sounds at least like very annoying behaviour.
EDIT: Nevermind me asking for your OS, I ignored the subject line, sorry!