diff --git a/bzGraflow.js b/bzGraflow.js
index cbfacc7..55d8ea3 100644
--- a/bzGraflow.js
+++ b/bzGraflow.js
@@ -155,30 +155,24 @@ class BZgraflow extends Buildoz{
         })
     
         const layers = this.computeLayers(this.flow.nodes, parents)
-//        const maxLayers = Math.max(...layers.map(item=>item.length))
         let maxHeight = 0
         const layerHeights = []
+        const indexes = {} // Todo: a
         for(const layer of layers){
             let totHeight = 0
-            for(const nid of layer){
+            for(const [idx, nid] of layer.entries()){
                 const bb = this.stagedNodes[nid].getBoundingClientRect()
                 totHeight += bb.height+gapy
+                indexes[nid] = idx 
             }
             if(totHeight>maxHeight) maxHeight = totHeight
             layerHeights.push(totHeight)
         }
+        
+        this.reorderLayers(layers, parents, indexes)
 
         let x = gapx
         for(const [idx, layer] of layers.entries()){
-            for(const nid of layer){
-                // some parents can be in far layers, but at least one is in the prev layer (by definition of layer)
-                const localParent = parents[nid].find((nid => layers[idx-1].includes(nid)))
-                if(localParent){ //undefined for 1st node
-                    const ports = this.stagedNodes[localParent].ports
-                    console.log(`parent of ${nid} is ${localParent}`, ports)
-                }
-            }
-
             let wMax = 0
             let y = ((maxHeight - layerHeights[idx]) / 2) + gapy
             for(const nid of layer){
@@ -191,7 +185,32 @@ class BZgraflow extends Buildoz{
         }
     }
 
-    moveNode(nid, destx, desty, duration = 200) {
+    reorderLayers(layers, parents, indexes){
+        const swap = (vect, todo) => {
+            for(const s of todo){
+                [vect[s[0]], vect[s[1]]] = [vect[s[1]], vect[s[0]]]
+            }
+        }
+        for(const [lidx, layer] of layers.entries()){
+            if(lidx==0) continue
+            const toSwap = []
+            for(let i=0; i<layer.length; i++){
+                const nid1 = layer[i]
+                // some parents can be in far layers, but at least one is in the prev layer (by definition of layer)
+                const pnid1 = parents[nid1].find((nid => layers[lidx-1].includes(nid)))
+                for(let j=i+1; j<layer.length; j++){
+                    const nid2 = layer[j]
+                    const pnid2 = parents[nid2].find((nid => layers[lidx-1].includes(nid)))
+                    if(((indexes[pnid1] - indexes[pnid2]) * (indexes[nid1] - indexes[nid2])) < 0) { // crossing !
+                        toSwap.push([i, j])
+                    }
+                }
+            }
+            swap(layer, toSwap)
+        }
+    }
+
+    moveNode(nid, destx, desty, duration = 200, cb) {
         const t0 = performance.now()
         const bb = this.stagedNodes[nid].getBoundingClientRect()
         const x0=bb.x
@@ -275,5 +294,3 @@ class BZgraflow extends Buildoz{
     
 }
 Buildoz.define('graflow', BZgraflow)
-
-