I am a graduate student thinking about some stuff. If I have an idea for a result but it is not yet complete, how safe is it to mention it to others (especially more experienced people)? What I mean is: is it possible that he/she will take it, develop it quicker than I do and publish it? How should one behave in these situations?

I didn't have a problem with my first paper but I always worry about these things. Should I?

I am a graduate student thinking about some stuff.

1. If I have an idea for a result but it is not yet complete, is it advisable to mention it to others (especially more experienced people)? Is it possible that he/she will take it, develop it quicker than I do and publish it? How should one behave in these situations?

2. Is there a rule of thumb about when (and how) to mention your ideas to others in the community?

3. How often does it happen that a student's idea is hijacked by a more experienced mathematician?