Curtain wall cutting planes

[Anonymous]

Recently I ran into one more issue working with curtain walls. I have not typical corner and two curtain wall panels intersecting in it. Also the corner should be glazed(without frame) so I deleted boundary at that place (made invisible).
But mullions still left I have tried to cut them with cutting planes function but it only cuts half of the mullion. You can see how corner looks in the screenshot. Has anyone met this or similar problem before? Any solutions?
P.S. I can not use polylined curtain wall method in this place because of the form.

[Laszlo Nagy]

Why don't you set those still visible mullions to "Invisible"?
Then you would not need to use those cutting planes.

[Anonymous]

The problem with removal of the mullions is that then instead of them I have empty lines where mullions supposed to be. Of course graphically this method is better. Thank you