I am working on a solution for the above problem. Without success by now.
To draw it within OnMouseMove with XOR-operation in not a good solution.
One problem: OnMouseMove is not called if the mouse moves to outside the CView-window.
But in this case the crosshairs should be deleted.
Second: working with XOR will not be good because we need a defined state (visible/not visible).

Any ideas for the implementation?