fix pixelsPerPoint.

Assets/UIWidgets/editor/editor_window.cs

                 this._lastPosition.width * EditorGUIUtility.pixelsPerPoint,
                 this._lastPosition.height * EditorGUIUtility.pixelsPerPoint);
 
-
             instance = this;
             try {
                 this._binding = new WidgetsBinding();
                 canvas = new CanvasImpl()
             };
             layer.paint(paintContext);
-            
+
             this._rasterCache.sweepAfterFrame();
         }
 

Assets/UIWidgets/rendering/layer.cs

     }
 
     public class TransformLayer : OffsetLayer {
-        public TransformLayer(Matrix4x4 transform = default(Matrix4x4), Offset offset = null) : base(offset) {
-            this._transform = transform;
+        public TransformLayer(Matrix4x4? transform = null, Offset offset = null) : base(offset) {
+            this._transform = transform ?? Matrix4x4.identity;
         }
 
         public Matrix4x4 transform {

Assets/UIWidgets/rendering/view.cs

         public readonly double devicePixelRatio;
 
         public Matrix4x4 toMatrix() {
-            return Matrix4x4.Scale(new Vector3(
-                (float) this.devicePixelRatio, (float) this.devicePixelRatio, 1));
+            return Matrix4x4.identity;
         }
 
         public override string ToString() {

Assets/UIWidgets/ui/painting/canvas_impl.cs

         }
 
         public CanvasImpl() {
-            this._transform = Matrix4x4.Scale(new Vector3(
-                1.0f / EditorGUIUtility.pixelsPerPoint,
-                1.0f / EditorGUIUtility.pixelsPerPoint,
-                1.0f));
-
+            this._transform = Matrix4x4.identity;
             this._defaultTexture = RenderTexture.active;
         }
 
                     var drawPicture = (DrawPicture) drawCmd;
                     this.drawPicture(drawPicture.picture);
                 } else if (drawCmd is DrawConcat) {
-                    var drawConcat = (DrawConcat) drawCmd; 
+                    var drawConcat = (DrawConcat) drawCmd;
                     this.concat(drawConcat.transform);
                 } else if (drawCmd is DrawSetMatrix) {
                     var drawSetMatrix = (DrawSetMatrix) drawCmd;
             this.pushClipRRect(rect, this._transform);
         }
 
-        public void drawTextBlob(TextBlob textBlob, Offset offset)
-        {
+        public void drawTextBlob(TextBlob textBlob, Offset offset) {
             var mesh = MeshGenrator.generateMesh(textBlob);
             var font = FontManager.instance.getOrCreate(textBlob.style.fontFamily).font;
             prepareGL(font.material);
             }
 
             var textBlobOffset = textBlob.positions[textBlob.start];
-            
+
             Graphics.DrawMeshNow(mesh, this._transform * Matrix4x4.Translate(
                                            new Vector3((float) Utils.PixelCorrectRound(offset.dx + textBlobOffset.x),
                                                (float) Utils.PixelCorrectRound(offset.dy + textBlobOffset.y), 0)));