ActivityIndicator as modal

I have a 2 pickers and a few buttons on a page. Once I click button A, I show an activity indicator till a process is completed. Visibility and IsRunning property of this activityIndicator are bound to a property of a VM. However I have 2 questions-

• while Activity Indicator is running, all pickers and controls are still enabled. I tried binding the isEnabled property on pickers to same property as activityIndicator's IsRunning is bound to. However then I couldnt even see my activityIndicator.

• Is there a way to show activityIndicator as modal so that the whole page in background is disabled.

I am using Xamarin.Forms 1.3.0

Thanks