I've been trying to implement your Floating Action Button. I've followed the instructions you've made. When I try to run my app I get: Caused by: java.lang.ClassCastException: android.widget.ImageView cannot be cast to android.support.v7.widget.AppCompatImageView
I'm not sure if it's something on my side, or on the main source code. The error is pointing at line 52 in your FabOptionsContainer.
Thanks in advance!