Hi Matadem, also for finding where the opening is located on an open curve there is a plugin here that can be helpful:
http://moi3d.com/forum/index.php?webtag=MOI&msg=2888.11

That marks the start point of an open curve with a point object.

And yes for transferring between 2 open windows use copy / paste (ctrl+c/ctrl+v).

- Michael