Device screen now has the ability to hide and clear the canvas.

res/app/components/stf/screen/screen-controller.js

@@ -1,19 +1,5 @@
 module.exports = function DeviceScreenCtrl($scope, $rootScope, ScalingService) {
   $scope.displayError = false
-  $scope.canView = true
-  $scope.showScreen = true
   $scope.ScalingService = ScalingService
 
-  var deregisterPageHidden = $rootScope.$on('pageHidden', function () {
-    $scope.canView = false
-  })
-
-  var deregisterPageVisible = $rootScope.$on('pageVisible', function () {
-    $scope.canView = true
-  })
-
-  $scope.$on('$destroy', function() {
-    deregisterPageHidden()
-    deregisterPageVisible()
-  })
 }