Set window.app as default value for button group option "app".

doc/out/pixi_button.js.html

@@ -1705,10 +1705,10 @@ export default class Button extends PIXI.Container {
         })
 
         this.button.on('pointerout', this.onEnd.bind(this))
-		this.button.on('pointercancel', this.onEnd.bind(this))
-		this.button.on('pointerupoutside', this.onEnd.bind(this))
-		this.button.on('pointertap', this.onEnd.bind(this))
-		this.button.on('scroll', this.onEnd.bind(this))
+        this.button.on('pointercancel', this.onEnd.bind(this))
+        this.button.on('pointerupoutside', this.onEnd.bind(this))
+        this.button.on('pointertap', this.onEnd.bind(this))
+        this.button.on('scroll', this.onEnd.bind(this))
 
         // eslint-disable-next-line no-unused-vars
         this.button.on('pointerdown', e => {
@@ -2141,14 +2141,14 @@ export default class Button extends PIXI.Container {
             this.icon.tint = value
         }
     }
-	
-	onEnd(event) {
-		this.capture(event)
-		TweenLite.to([this.button, this.content], this.theme.fast, {
-			alpha: 1,
-			overwrite: 'none'
-		})
-	}
+
+    onEnd(event) {
+        this.capture(event)
+        TweenLite.to([this.button, this.content], this.theme.fast, {
+            alpha: 1,
+            overwrite: 'none'
+        })
+    }
 }
 </code></pre>
         </article>
@@ -2163,7 +2163,7 @@ export default class Button extends PIXI.Container {
 
         <footer class="content-size">
             <div class="footer">
-                Documentation generated by <a href="https://github.com/jsdoc3/jsdoc">JSDoc 3.6.3</a> on Fri Aug 02 2019 10:15:07 GMT+0200 (Mitteleuropäische Sommerzeit)
+                Documentation generated by <a href="https://github.com/jsdoc3/jsdoc">JSDoc 3.6.3</a> on Mon Aug 05 2019 11:44:33 GMT+0200 (Mitteleuropäische Sommerzeit)
             </div>
         </footer>
     </div>