Merge pull request #26792 from TizioFittizio/master

[ReactNavigation] Values added for event argument in addListener

types/react-navigation/index.d.ts

@@ -17,6 +17,7 @@
 //                 Ciaran Liedeman <https://github.com/cliedeman>
 //                 Edward Sammut Alessi <https://github.com/Slessi>
 //                 Jérémy Magrin <https://github.com/magrinj>
+//                 Luca Campana <https://github.com/TizioFittizio>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.6
 
@@ -578,7 +579,7 @@ export interface NavigationScreenProp<S, P = NavigationParams> {
   getParam: <T extends keyof P>(param: T, fallback?: P[T]) => P[T];
   setParams: (newParams: Partial<P>) => boolean;
   addListener: (
-    eventName: string,
+    eventName: 'willBlur' | 'willFocus' | 'didFocus' | 'didBlur',
     callback: NavigationEventCallback
   ) => NavigationEventSubscription;
   push: (