Prevent dragging of button group if buttons are not wider than maxWidth.

lib/pixi/buttongroup.html

@@ -30,7 +30,7 @@
 const app = new PIXIApp({
     view: canvas,
     width: 1000,
-    height: 1400
+    height: 1700
 }).setup().run()
 
 const buttonGroup1 = new ButtonGroup({
@@ -324,12 +324,24 @@ const buttonGroup18 = new ButtonGroup({
     app
 })
 
+const buttonGroup19 = new ButtonGroup({
+    x: 10,
+    y: 1420,
+    buttons: [
+        {label: 'move'},
+        {label: 'explanation dried'},
+        {label: 'out catch'}
+    ],
+    maxWidth: 500,
+    app
+})
+
 app.scene.addChild(buttonGroup1, buttonGroup2, buttonGroup3)
 app.scene.addChild(buttonGroup4)
 app.scene.addChild(buttonGroup5, buttonGroup6)
 app.scene.addChild(buttonGroup7, buttonGroup8)
 app.scene.addChild(buttonGroup9, buttonGroup10, buttonGroup11, buttonGroup12, buttonGroup13)
-app.scene.addChild(buttonGroup14, buttonGroup15, buttonGroup16, buttonGroup17, buttonGroup18)
+app.scene.addChild(buttonGroup14, buttonGroup15, buttonGroup16, buttonGroup17, buttonGroup18, buttonGroup19)
     </script>
 </body>
 </html>