Qigong and the practise of Tibetan buddhism?

I have heard that one shouldnt practise diffrent kinds of cultivation systems in the same time (like Falungong and Yoga).
I have been doing yoga for about 2 years but Im considering trying qigong. Does anybody know if the cultivation systems of Vajrayana and qigong is "opposing" eachother? I have heard that qigong is practised in Tibet, is this true?
Anybody here thats practising Vajrayana and qigong?

And does anybody know of any good qigong messgeboard/forum where I could ask this question?