How to obtain and manipulate QMesh vertices, faces, something else?

Hi there.
I got arbitrary solid QMesh on my screen using examples. It's great. But I can to do nothing with it. mesh->children().count = 0, mesh->primitiveCount=0, mesh->geometry()=0 and so on. How to obtain internal contents of QMesh? Can I change QMesh vertices (geometry) programmatically, on the fly? The "setSource()" does not seems sufficient for all occasions. I wonder something similar to mesh->getVertices(), mesh->getBones(), getFaces()... and so on. Any form of geometrical descriptions of the body (solid) within the mesh.