Hi Pilou - is your goal to select one ring of points?

If so, then try switching to one of the ortho views, like the Front or Right view where you can more easily grab a selection window around one ring.

Also you can do it in the 3D view if you tilt your view a bit, like this:



Hope that helps! I do want to add some other kinds of selection tools in the future but for now you would need to use this method.

- Michael