Add defaults for background, width and height

projects/common/models/slider-element.ts

@@ -26,10 +26,10 @@ export class SliderElement extends InputElement implements FontElement, SurfaceU
     registerLocaleData(localeDe);
     Object.assign(this, serializedElement);
     Object.assign(this, initFontElement(serializedElement));
-    if (!serializedElement.backgroundColor) {
-      serializedElement.backgroundColor = '#d3d3d300';
-    }
     Object.assign(this, initSurfaceElement(serializedElement));
-    // todo: delete this.label --> label must be declared as optional
+
+    this.height = serializedElement.height || 70;
+    this.width = serializedElement.width || 300;
+    this.backgroundColor = serializedElement.backgroundColor as string || '#d3d3d300';
   }
 }

projects/common/util/element.factory.ts

@@ -10,7 +10,6 @@ import { RadioButtonGroupElement } from '../models/radio-button-group-element';
 import { ImageElement } from '../models/image-element';
 import { AudioElement } from '../models/audio-element';
 import { VideoElement } from '../models/video-element';
-import { FileService } from '../file.service';
 import { TextComponent } from '../element-components/text.component';
 import { ButtonComponent } from '../element-components/button.component';
 import { TextFieldComponent } from '../element-components/text-field.component';
@@ -28,7 +27,7 @@ import { RadioGroupImagesElement } from '../models/compound-elements/radio-group
 import { DropListComponent } from '../element-components/compound-elements/drop-list.component';
 import { DropListElement } from '../models/compound-elements/drop-list';
 import { SliderElement } from '../models/slider-element';
-import {SliderComponent} from "../element-components/slider.component";
+import { SliderComponent } from '../element-components/slider.component';
 
 export function createElement(elementModel: UIElement): UIElement {
   let newElement: UIElement;