Update Type Compatibility.md

packages/documentation/copy/en/reference/Type Compatibility.md

@@ -168,7 +168,28 @@ listenEvent(EventType.Mouse, ((e: MyMouseEvent) =>
 listenEvent(EventType.Mouse, (e: number) => console.log(e));
 ```
 
-You can have TypeScript raise errors when this happens via the compiler flag [`strictFunctionTypes`](/tsconfig#strictFunctionTypes).
+You can have TypeScript raise errors when this happens via the compiler flag [`strictFunctionTypes`](/tsconfig#strictFunctionTypes).  
+
+A sound approach that works with the `strictFunctionTypes` flag is to use conditional types:
+```
+// Assuming EventType, Event, MyMouseEvent, and MyKeyEvent as above
+
+type GenericEvent<E extends EventType> = E extends EventType.Mouse ? MyMouseEvent : MyKeyEvent
+
+function listenEvent<E extends EventType>(eventType: E, handler: (n: GenericEvent<E>) => void): void;
+function listenEvent(eventType: EventType, handler: (n: GenericEvent<typeof eventType>) => void): void {
+  /* ... */
+}
+
+// Valid
+listenEvent(EventType.Mouse, (e: MyMouseEvent) => console.log(e.x + "," + e.y));
+// Valid
+listenEvent(EventType.Keyboard, (e: MyKeyEvent) => console.log(e.keyCode));
+// Invalid
+listenEvent(EventType.Mouse, (e: MyKeyEvent) => console.log(e.keyCode));
+// Invalid
+listenEvent(EventType.Mouse, (e: Event) => console.log(e.x + "," + e.y));
+```
 
 ### Optional Parameters and Rest Parameters