mxCompactTreeLayout.prototype.merge=function(a,b){for(var c=0,d=0,e=0,f=a.lowerHead,g=b.upperHead;null!=g&&null!=f;){var k=this.offset(c,d,g.dx,g.dy,f.dx,f.dy);d+=k;e+=k;c+g.dx<=f.dx?(c+=g.dx,d+=g.dy,g=g.next):(c-=f.dx,d-=f.dy,f=f.next)}null!=g?(c=this.bridge(a.upperTail,0,0,g,c,d),a.upperTail=null!=c.next?b.upperTail:c,a.lowerTail=b.lowerTail):(c=this.bridge(b.lowerTail,c,d,f,0,0),null==c.next&&(a.lowerTail=c));a.lowerHead=b.lowerHead;return e};