app: [API] refactor app.ViewEvent to support wayland

This commit changes the definition of app.ViewEvent on Unix systems
to be an interface implemented by two different concrete types:
X11ViewEvent and WaylandViewEvent. Each provides the necessary fields
for custom rendering on its display protocol.

This is a breaking change for all users of app.ViewEvent on
Linux/BSD, as it now is an interface instead of a concrete type.

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

app/os_wayland.go

@@ -248,12 +248,19 @@ func newWLWindow(callbacks *callbacks, options []Option) error {
 		defer w.destroy()
 
 		w.w.SetDriver(w)
+
 		// Finish and commit setup from createNativeWindow.
 		w.Configure(options)
 		C.wl_surface_commit(w.surf)
-		if err := w.loop(); err != nil {
-			panic(err)
-		}
+
+		w.w.Event(WaylandViewEvent{
+			Display: unsafe.Pointer(w.display()),
+			Surface: unsafe.Pointer(w.surf),
+		})
+		defer w.w.Event(WaylandViewEvent{})
+
+		err := w.loop()
+		w.w.Event(system.DestroyEvent{Err: err})
 	}()
 	return nil
 }
@@ -1308,7 +1315,6 @@ func (w *window) loop() error {
 		default:
 		}
 		if w.dead {
-			w.w.Event(system.DestroyEvent{})
 			break
 		}
 		w.draw()