message: vuejs
  -- fixed file;
diff: <div>
  <input v-if="isEditMode" type="file" :id="question.inputId" @change="doChange"/>
  <div>
  - <img v-show="question.previewValue" :src="previewSrc" :height="question.imageHeight" :width="question.imageWidth"/>
  + <img v-show="question.previewValue" :src="question.value" :height="question.imageHeight" :width="question.imageWidth"/>
  </div>
  </div>
  </template>
  @Component
  export default class File extends Question<QuestionFileModel> {
  - previewSrc = null
  -
  - mounted() {
  - this.question.valueChangedCallback = this.onValueChanged;
  - }
  - beforeDestroy() {
  - this.question.valueChangedCallback = undefined; // TODO: ensure this works
  - }
  -
  - onValueChanged() {
  - this.previewSrc = this.question.value;
  - }
  -
  doChange (e) {
  var src = e.target || e.srcElement;
  if (!window["FileReader"]) return;
  