Fix showing empty FAB

app/src/main/java/org/solovyev/android/calculator/view/PagerViewFabBehavior.java

@@ -22,6 +22,9 @@ public class PagerViewFabBehavior extends FloatingActionButton.Behavior {
     @Override
     public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout,
             FloatingActionButton child, View directTargetChild, View target, int nestedScrollAxes) {
+        if (!child.isClickable()) {
+            return false;
+        }
         switch (nestedScrollAxes) {
             case ViewCompat.SCROLL_AXIS_HORIZONTAL:
                 return target instanceof ViewPager;

app/src/main/res/values/styles.xml

@@ -280,6 +280,7 @@
         <item name="android:layout_gravity">bottom|end</item>
         <item name="android:layout_margin">16dp</item>
         <item name="android:visibility">gone</item>
+        <item name="android:clickable">false</item>
         <item name="backgroundTint">?attr/cpp_fab_bg</item>
     </style>