diff --git a/web/app/sketcher/canvas.js b/web/app/sketcher/canvas.js
index 68226188..c469dbad 100644
--- a/web/app/sketcher/canvas.js
+++ b/web/app/sketcher/canvas.js
@@ -74,9 +74,12 @@ TCAD.TWO.Viewer = function(canvas) {
   window.addEventListener( 'resize', onWindowResize, false );
   
   this.ctx = this.canvas.getContext("2d");
+  this._activeLayer = null;
   this.layers = [];
   this._serviceLayers = [];
-  this._workspace = [this.layers, this._serviceLayers];
+  this.dimLayer = new TCAD.TWO.Layer("_dim", TCAD.TWO.Styles.DIM);
+  this.dimLayers = [this.dimLayer];
+  this._workspace = [this.dimLayers, this.layers, this._serviceLayers];
   this.toolManager = new TCAD.TWO.ToolManager(this, new TCAD.TWO.PanTool(this));
   this.parametricManager = new TCAD.TWO.ParametricManager(this);
 
@@ -87,8 +90,6 @@ TCAD.TWO.Viewer = function(canvas) {
   this.snapped = [];
   
   this._setupServiceLayer();
-  this.dimLayer = new TCAD.TWO.Layer("_dim", TCAD.TWO.Styles.DIM);
-  this.layers.push(this.dimLayer);
 
   this.refresh();
 };
@@ -317,6 +318,21 @@ TCAD.TWO.Viewer.prototype.mark = function(obj, style) {
   this.selected.push(obj);
 };
 
+TCAD.TWO.Viewer.prototype.activeLayer = function() {
+  var layer = this._activeLayer;
+  if (layer == null) {
+    if (this.layers.length == 0) {
+      this.layers.push(new TCAD.TWO.Layer("JustALayer", TCAD.TWO.Styles.DEFAULT));
+    }
+    layer = this.layers[0];
+  }
+  return layer;
+};
+
+TCAD.TWO.Viewer.prototype.setActiveLayer = function(layer) {
+  this._activeLayer = layer;
+};
+
 TCAD.TWO.Viewer.prototype.deselectAll = function() {
   for (var i = 0; i < this.selected.length; i++) {
     this.selected[i].marked = null;
diff --git a/web/app/sketcher/main2d.js b/web/app/sketcher/main2d.js
index bc270eb7..0729a02d 100644
--- a/web/app/sketcher/main2d.js
+++ b/web/app/sketcher/main2d.js
@@ -6,7 +6,6 @@ TCAD.App2D = function() {
   this.viewer = new TCAD.TWO.Viewer(document.getElementById('viewer'));
   this.boundaryLayer = new TCAD.TWO.Layer("default", TCAD.TWO.Styles.DEFAULT);
   this.viewer.layers.push(this.boundaryLayer);
-
   var app = this;
 
   this.actions = {};
@@ -17,26 +16,26 @@ TCAD.App2D = function() {
   this.registerAction = function(id, desc, action) {
     app.actions[id] = {id: id, desc: desc, action: action};
     app._actionsOrder.push(id);
-  }
+  };
 
   this.registerAction('addPoint', "Add Point", function () {
-    app.viewer.toolManager.takeControl(new TCAD.TWO.AddPointTool(app.viewer, layer));
+    app.viewer.toolManager.takeControl(new TCAD.TWO.AddPointTool(app.viewer));
   });
   
   this.registerAction('addSegment', "Add Segment", function () {
-    app.viewer.toolManager.takeControl(new TCAD.TWO.AddSegmentTool(app.viewer, layer, false));
+    app.viewer.toolManager.takeControl(new TCAD.TWO.AddSegmentTool(app.viewer, false));
   });
 
   this.registerAction('addMultiSegment', "Add Multi Segment", function () {
-    app.viewer.toolManager.takeControl(new TCAD.TWO.AddSegmentTool(app.viewer, layer, true));
+    app.viewer.toolManager.takeControl(new TCAD.TWO.AddSegmentTool(app.viewer, true));
   });
 
   this.registerAction('addArc', "Add Arc", function () {
-    app.viewer.toolManager.takeControl(new TCAD.TWO.AddArcTool(app.viewer, layer));
+    app.viewer.toolManager.takeControl(new TCAD.TWO.AddArcTool(app.viewer));
   });
 
   this.registerAction('addCircle', "Add Circle", function () {
-    app.viewer.toolManager.takeControl(new TCAD.TWO.EditCircleTool(app.viewer, layer));
+    app.viewer.toolManager.takeControl(new TCAD.TWO.EditCircleTool(app.viewer));
   });
 
   this.registerAction('pan', "Pan", function () {
@@ -61,28 +60,32 @@ TCAD.App2D = function() {
       function point(p) {
         return [ p.id, [p._x.id, p.x], [p._y.id, p.y] ];
       }
-      for (var l = 0; l < app.viewer.layers.length; ++l) {
-        var layer = app.viewer.layers[l];
-        var isBoundary = layer.name === '';
-        var toLayer = {name : layer.name, data : []};
-        sketch.layers.push(toLayer);
-        for (var i = 0; i < layer.objects.length; ++i) {
-          var obj = layer.objects[i];
-          var to = {id: obj.id, _class: obj._class};
-          if (obj.aux) to.aux = obj.aux;
-          if (obj.edge !== undefined) to.edge = obj.edge;
-          toLayer.data.push(to);
-          if (obj._class === 'TCAD.TWO.Segment') {
-            to.points = [point(obj.a), point(obj.b)];
-          } else if (obj._class === 'TCAD.TWO.Arc') {
-            to.points = [point(obj.a), point(obj.b), point(obj.c)];
-          } else if (obj._class === 'TCAD.TWO.Circle') {
-            to.c = point(obj.c);
-            to.r = obj.r.get();
-          } else if (obj._class === 'TCAD.TWO.Dimension' || obj._class === 'TCAD.TWO.HDimension' || obj._class === 'TCAD.TWO.VDimension') {
-            to.a = obj.a.id;
-            to.b = obj.b.id;
-            to.flip = obj.flip; 
+      var toSave = [app.viewer.dimLayers, app.viewer.layers]
+      for (var t = 0; t < toSave.length; ++t) {
+        var layers = toSave[t]; 
+        for (var l = 0; l < layers.length; ++l) {
+          var layer = layers[l];
+          var isBoundary = layer.name === '';
+          var toLayer = {name : layer.name, data : []};
+          sketch.layers.push(toLayer);
+          for (var i = 0; i < layer.objects.length; ++i) {
+            var obj = layer.objects[i];
+            var to = {id: obj.id, _class: obj._class};
+            if (obj.aux) to.aux = obj.aux;
+            if (obj.edge !== undefined) to.edge = obj.edge;
+            toLayer.data.push(to);
+            if (obj._class === 'TCAD.TWO.Segment') {
+              to.points = [point(obj.a), point(obj.b)];
+            } else if (obj._class === 'TCAD.TWO.Arc') {
+              to.points = [point(obj.a), point(obj.b), point(obj.c)];
+            } else if (obj._class === 'TCAD.TWO.Circle') {
+              to.c = point(obj.c);
+              to.r = obj.r.get();
+            } else if (obj._class === 'TCAD.TWO.Dimension' || obj._class === 'TCAD.TWO.HDimension' || obj._class === 'TCAD.TWO.VDimension') {
+              to.a = obj.a.id;
+              to.b = obj.b.id;
+              to.flip = obj.flip; 
+            }
           }
         }
       }
@@ -209,19 +212,23 @@ TCAD.App2D.prototype.loadSketch = function(sketch) {
 
     var layerIdGen = 0;
     function getLayer(viewer, name) {
-      for (var i = 0; i < viewer.layers.length; ++i) {
-        if (name === viewer.layers[i].name) {
-          return viewer.layers[i];
-        }
-      }
       if (name === undefined) {
         name = "layer_" + layerIdGen++;
+      } else {
+        if (name === viewer.dimLayer.name) {
+          return viewer.dimLayer;
+        }
+        for (var i = 0; i < viewer.layers.length; ++i) {
+          if (name === viewer.layers[i].name) {
+            return viewer.layers[i];
+          }
+        }
       }
       var layer = new TCAD.TWO.Layer(name, TCAD.TWO.Styles.DEFAULT);
       viewer.layers.push(layer);
       return layer;
     }
-  
+    var activeLayerCandidate = this.viewer.layers.length;
     if (sketch.layers !== undefined) {
       for (var l = 0; l < sketch.layers.length; ++l) {
         var layer = getLayer(this.viewer, sketch.layers[l].name);
@@ -264,17 +271,14 @@ TCAD.App2D.prototype.loadSketch = function(sketch) {
         }
       }
     }
-
-    for (l = 0; l < this.viewer.layers.length; ++l) {
-      layer = this.viewer.layers[l];
-      for (i = 0; i < layer.objects.length; ++i) {
-        obj = layer.objects[i];
-        if (obj._class === 'TCAD.TWO.Dimension' || obj._class === 'TCAD.TWO.HDimension' || obj._class === 'TCAD.TWO.VDimension') {
-          obj.a = index[obj.a];
-          obj.b = index[obj.b];
-        }
-      }
-    }  
+  
+    for (i = 0; i < this.viewer.dimLayer.objects.length; ++i) {
+      obj = this.viewer.dimLayer.objects[i];
+      //if (obj._class === 'TCAD.TWO.Dimension' || obj._class === 'TCAD.TWO.HDimension' || obj._class === 'TCAD.TWO.VDimension') {
+        obj.a = index[obj.a];
+        obj.b = index[obj.b];
+      //}
+    }
 
     if (sketch.boundary !== undefined && sketch.boundary != null) {
       this.updateBoundary(sketch.boundary);
@@ -287,6 +291,9 @@ TCAD.App2D.prototype.loadSketch = function(sketch) {
       }
       this.viewer.parametricManager.notify();
     }
+    if (activeLayerCandidate < this.viewer.layers.length) {
+      this.viewer.setActiveLayer(this.viewer.layers[activeLayerCandidate]);
+    }
 };
 
 TCAD.App2D.prototype.updateBoundary = function (boundary) {
diff --git a/web/app/sketcher/parametric.js b/web/app/sketcher/parametric.js
index 97c3cfc2..06208118 100644
--- a/web/app/sketcher/parametric.js
+++ b/web/app/sketcher/parametric.js
@@ -53,6 +53,14 @@ TCAD.TWO.ParametricManager.prototype._add = function(constr) {
     break;  
   }
   subSystem.constraints.push(constr);
+  this.checkRedundancy(subSystem, constr);
+};
+
+TCAD.TWO.ParametricManager.prototype.checkRedundancy = function (subSystem, constr) {
+  var solver = this.prepareForSubSystem([], subSystem);
+  if (TCAD.parametric.diagnose(solver.system).conflict) {
+    alert("Most likely this "+constr.NAME + "." + constr.id +" constraint is CONFLICTING!")
+  }
 };
 
 TCAD.TWO.ParametricManager.prototype.refresh = function() {
@@ -79,7 +87,7 @@ TCAD.TWO.ParametricManager.prototype.remove = function(constr) {
     for (var i = 0; i < sub.constraints.length; ++i) {
       var p = sub.constraints[i];
       if (p === constr) {
-        sub.constraints(i, 1);
+        sub.constraints.splice(i, 1);
         if (p.NAME === 'coi') {
           this.unlinkObjects(p.a, p.b);
         }
diff --git a/web/app/sketcher/shapes/arc.js b/web/app/sketcher/shapes/arc.js
index 436a81bc..41911ff6 100644
--- a/web/app/sketcher/shapes/arc.js
+++ b/web/app/sketcher/shapes/arc.js
@@ -71,9 +71,8 @@ TCAD.TWO.Arc.prototype.stabilize = function(viewer) {
   viewer.parametricManager._add(new TCAD.TWO.Constraints.P2PDistanceV(this.a, this.c, this.r));
 };
 
-TCAD.TWO.AddArcTool = function(viewer, layer) {
+TCAD.TWO.AddArcTool = function(viewer) {
   this.viewer = viewer;
-  this.layer = layer;
   this.arc = null;
   this.point = null;
   this._v = new TCAD.Vector(0, 0, 0);
@@ -120,7 +119,7 @@ TCAD.TWO.AddArcTool.prototype.mouseup = function(e) {
       new TCAD.TWO.EndPoint(p.x, p.y)
     );
     this.point = this.arc.a;
-    this.layer.objects.push(this.arc);
+    this.viewer.activeLayer().objects.push(this.arc);
     this.viewer.refresh();
   } else if (this.point.id === this.arc.a.id) {
     this.point = this.arc.b;
diff --git a/web/app/sketcher/shapes/circle.js b/web/app/sketcher/shapes/circle.js
index 6c03064b..3c2d4d67 100644
--- a/web/app/sketcher/shapes/circle.js
+++ b/web/app/sketcher/shapes/circle.js
@@ -41,9 +41,8 @@ TCAD.TWO.Circle.prototype.getDefaultTool = function(viewer) {
 };
 
 
-TCAD.TWO.EditCircleTool = function(viewer, layer) {
+TCAD.TWO.EditCircleTool = function(viewer) {
   this.viewer = viewer;
-  this.layer = layer;
   this.circle = null;
 };
 
@@ -76,7 +75,7 @@ TCAD.TWO.EditCircleTool.prototype.mouseup = function(e) {
     this.circle = new TCAD.TWO.Circle(
       new TCAD.TWO.EndPoint(p.x, p.y)
     );
-    this.layer.objects.push(this.circle);
+    this.viewer.activeLayer().objects.push(this.circle);
     this.viewer.refresh();
   } else {
     this.solveRequest(false);
diff --git a/web/app/sketcher/shapes/segment.js b/web/app/sketcher/shapes/segment.js
index 9f86b3a5..16cc2023 100644
--- a/web/app/sketcher/shapes/segment.js
+++ b/web/app/sketcher/shapes/segment.js
@@ -1,7 +1,6 @@
 
-TCAD.TWO.AddSegmentTool = function(viewer, layer, multi) {
+TCAD.TWO.AddSegmentTool = function(viewer, multi) {
   this.viewer = viewer;
-  this.layer = layer;
   this.line = null;
   this.multi = multi;
 };
@@ -38,7 +37,7 @@ TCAD.TWO.AddSegmentTool.prototype.mouseup = function(e) {
       this.viewer.cleanSnap();
       needSnap = true;
     }
-    this.line = this.viewer.addSegment(a.x, a.y, b.x, b.y, this.layer);
+    this.line = this.viewer.addSegment(a.x, a.y, b.x, b.y, this.viewer.activeLayer());
     if (needSnap) {
       this.viewer.parametricManager.linkObjects([this.line.a, a]);
     }
@@ -54,7 +53,7 @@ TCAD.TWO.AddSegmentTool.prototype.mouseup = function(e) {
     }
     if (this.multi) {
       var b = this.line.b; 
-      this.line = this.viewer.addSegment(b.x, b.y, b.x, b.y, this.layer);
+      this.line = this.viewer.addSegment(b.x, b.y, b.x, b.y, this.viewer.activeLayer());
       this.viewer.parametricManager.linkObjects([this.line.a, b]);
     } else {
       this.line = null;
@@ -77,9 +76,8 @@ TCAD.TWO.AddSegmentTool.prototype.keypress = function(e) {};
 TCAD.TWO.AddSegmentTool.prototype.keyup = function(e) {};
 
 
-TCAD.TWO.AddPointTool = function(viewer, layer) {
+TCAD.TWO.AddPointTool = function(viewer) {
   this.viewer = viewer;
-  this.layer = layer;
 };
 
 TCAD.TWO.AddPointTool.prototype.mousemove = function(e) {
@@ -94,8 +92,9 @@ TCAD.TWO.AddPointTool.prototype.mousedown = function(e) {
 TCAD.TWO.AddPointTool.prototype.mouseup = function(e) {
   var a = this.viewer.screenToModel(e);
   var p = new TCAD.TWO.EndPoint(a.x, a.y);
-  this.layer.objects.push(p);
-  p.layer = this.layer;
+  var layer = this.viewer.activeLayer();
+  layer.objects.push(p);
+  p.layer = layer;
   this.viewer.refresh();
 };