Use dropdown instead of buttons for discriminator switch

lib/components/JsonSchema/json-schema.html

@@ -29,10 +29,10 @@
         <div class="param-description" innerHtml="{{prop.description | marked}}"></div>
         <div class="discriminator-info" *ngIf="prop.isDiscriminator">
           <span>This field value determines the exact schema:</span>
-          <ul>
-            <li *ngFor="#derived of schema.derived"
-            (click)="selectDerived(derived)" [ngClass]="{active: derived.active}"> {{derived.name}} </li>
-          </ul>
+          <dropdown (change)="selectDerived($event)">
+            <option *ngFor="#derived of schema.derived; #i=index"
+            [value]="i">{{derived.name}}</option>
+          </dropdown>
         </div>
       </td>
     </tr>

lib/components/JsonSchema/json-schema.js

@@ -3,14 +3,14 @@
 import {ElementRef} from 'angular2/core';
 
 import {RedocComponent, BaseComponent, SchemaManager} from '../base';
-import {Tabs, Tab} from '../../common/components/Tabs/tabs';
+import {DropDown} from '../../common/components/DropDown/dropdown';
 import JsonPointer from '../../utils/JsonPointer';
 
 @RedocComponent({
   selector: 'json-schema',
   templateUrl: './lib/components/JsonSchema/json-schema.html',
   styleUrls: ['./lib/components/JsonSchema/json-schema.css'],
-  directives: [JsonSchema, Tabs, Tab],
+  directives: [JsonSchema, DropDown],
   inputs: ['isArray', 'final', 'nestOdd', 'childFor']
 })
 @Reflect.metadata('parameters', [[SchemaManager], [ElementRef]])
@@ -21,8 +21,9 @@ export default class JsonSchema extends BaseComponent {
     this.final = false;
   }
 
-  selectDerived(subClass) {
-    if (subClass.active) return;
+  selectDerived(subClassIdx) {
+    let subClass = this.schema.derived[subClassIdx];
+    if (!subClass || subClass.active) return;
     this.schema.derived.forEach((subSchema) => {
       subSchema.active = false;
     });
@@ -62,7 +63,7 @@ export default class JsonSchema extends BaseComponent {
     }
 
     this.schema = schema;
-    if (schema.derived.length) this.selectDerived(schema.derived[0]);
+    this.selectDerived(0);
   }
 
   prepareObjectPropertiesData(schema) {