improve thread draw algorithm
improve thread draw algorithm

carolFrohlich/nipype,FCP-INDI/nipype,FCP-INDI/nipype,sgiavasis/nipype,mick-d/nipype,carolFrohlich/nipype,FCP-INDI/nipype,carolFrohlich/nipype,sgiavasis/nipype,carolFrohlich/nipype,sgiavasis/nipype,mick-d/nipype,FCP-INDI/nipype,sgiavasis/nipype,mick-d/nipype,mick-d/nipype