diff -r a9b9e6c7be63 -r 01f66ed90e32 client/js/paper-renderer.js
--- a/client/js/paper-renderer.js	Mon Feb 11 18:08:19 2013 +0100
+++ b/client/js/paper-renderer.js	Wed Feb 13 13:41:19 2013 +0100
@@ -235,6 +235,10 @@
     }
 }
 
+Rkns.Renderer._BaseRepresentation.prototype.resetCoords = function() {
+    this.paper_coords = undefined;
+}
+
 Rkns.Renderer.Node = Rkns.Utils.inherit(Rkns.Renderer._BaseRepresentation);
 
 Rkns.Renderer.Node.prototype._init = function() {
@@ -259,8 +263,10 @@
 }
 
 Rkns.Renderer.Node.prototype.redraw = function() {
-    var _model_coords = new paper.Point(this.model.get("position"));
-    this.paper_coords = this.renderer.toPaperCoords(_model_coords);
+    if (!this.paper_coords) {
+        var _model_coords = new paper.Point(this.model.get("position"));
+        this.paper_coords = this.renderer.toPaperCoords(_model_coords);
+    }
     this.circle.position = this.paper_coords;
     this.title.content = this.model.get("title");
     this.title.position = this.paper_coords.add([0, Rkns.Renderer._NODE_RADIUS + 1.5 *Rkns.Renderer._NODE_FONT_SIZE]);
@@ -313,15 +319,8 @@
 }
 
 Rkns.Renderer.Node.prototype.paperShift = function(_delta) {
-    var _coords = this.renderer.toModelCoords(this.paper_coords.add(_delta)),
-        _data = {
-            position: {
-                x: _coords.x,
-                y: _coords.y
-            }
-        };
-    this.model.set(_data);
-    //this.renderer.redraw();
+    this.paper_coords = this.paper_coords.add(_delta);
+    this.redraw();
 }
 
 Rkns.Renderer.Node.prototype.openEditor = function() {
@@ -369,8 +368,22 @@
     }
 }
 
+Rkns.Renderer.Node.prototype.saveCoords = function() {
+    var _coords = this.renderer.toModelCoords(this.paper_coords),
+        _data = {
+            position: {
+                x: _coords.x,
+                y: _coords.y
+            }
+        };
+    this.model.set(_data);
+}
+
 Rkns.Renderer.Node.prototype.mouseup = function(_event) {
-    if (!this.renderer.is_dragging) {
+    if (this.renderer.is_dragging) {
+        this.saveCoords();
+    }
+    else {
         this.openEditor();
     }
     this.renderer.click_target = null;
@@ -480,7 +493,10 @@
 }
 
 Rkns.Renderer.Edge.prototype.mouseup = function(_event) {
-    if (!this.renderer.is_dragging) {
+    if (this.renderer.is_dragging) {
+        this.from_representation.saveCoords();
+        this.to_representation.saveCoords();
+    } else {
         this.openEditor();
     }
     this.renderer.click_target = null;
@@ -490,7 +506,6 @@
 Rkns.Renderer.Edge.prototype.paperShift = function(_delta) {
     this.from_representation.paperShift(_delta);
     this.to_representation.paperShift(_delta);
-    this.renderer.redraw();
 }
 
 Rkns.Renderer.Edge.prototype.destroy = function() {
@@ -1095,6 +1110,7 @@
     
     paper.view.onResize = function(_event) {
         _this.offset = _this.offset.add(_event.delta.divide(2));
+        _this.resetCoords();
         _this.redraw();
     }
     
@@ -1170,6 +1186,7 @@
 
 Rkns.Renderer.Scene.prototype.setScale = function(_newScale) {
     this.scale = _newScale;
+    this.resetCoords();
     this.redraw();
 }
 
@@ -1192,6 +1209,12 @@
     }
 }
 
+Rkns.Renderer.Scene.prototype.resetCoords = function(_point) {
+    _(this.representations).each(function(r) {
+        r.resetCoords();
+    });
+}
+
 Rkns.Renderer.Scene.prototype.toPaperCoords = function(_point) {
     return _point.multiply(this.scale).add(this.offset);
 }
@@ -1312,6 +1335,7 @@
             this.click_target.paperShift(_event.delta);
         } else {
             this.offset = this.offset.add(_event.delta);
+            this.resetCoords();
             this.redraw();
         }
     } else {