if( p.u==0 && p.mo==p.r ){
          mergeLines[p.mo] = u.r<p.r ? -mergeOffset-mLine.w : mergeOffset;
        }else{
          mergeLines[p.mo] = -mLine.w/2;
        }
        x1 += mergeLines[p.mo]
        var y0 = p.y+2;
        var isCP = p.hasOwnProperty('cu');
        if( p.mu==p.id ){
          /* Merge out error to an existing riser from below */
          var dx = x1<x0 ? mArrow.w : -mArrow.w;
          if( isCP ){
            drawCherrypickLine(x0,y0,x1+dx,null);
            cls = "arrow cherrypick " + (x1<x0 ? "l" : "r");
          }else{
            drawMergeLine(x0,y0,x1+dx,null);
            cls = "arrow merge " + (x1<x0 ? "l" : "r");
          }
          if( p.mu==p.cu ){
            dx = x1<x0 ? mLine.w : -(mArrow.w + mLine.w/2);
            drawBox(cls,null,x1+dx,y0+(mLine.w-mArrow.h)/2);
          }
          y1 = y0;
        }else{
          drawMergeLine(x0,y0,x1+(x0<x1 ? mLine.w : 0),null);
          drawMergeLine(x1,y0+mLine.w,null,y1);
        }
        if( isCP ){
          var u2 = tx.rowinfo[p.cu-tx.iTopRow];
          var y2 = miLineY(u2);
          drawCherrypickLine(x1,y1,null,y2);
        }
      }else if( mergeOffset ){
        mergeLines[p.mo] = u.r<p.r ? -mergeOffset-mLine.w : mergeOffset;
        x1 += mergeLines[p.mo];