Student or Learner
What is the difference in meanings between 'in mind' and 'on mind'?
What is (on/ in) your mind?
What do you have in mind? is another idiom that means, "What are you thinking about?", except this one has the connotation of "What's your idea?" For example:
A: Are you busy tonight?What is in your mind? is only used in a very literal context - I can't think of a time that we would say this in normal conversation! (Maybe someone else can...)
B: Not really. What do you have in mind?