Fix T38467: Animation playback is not synchronized when Screen Layout changes

When both old and new screens share the same scene, "transfer" playback to new screen, else stop playback.

source/blender/editors/screen/screen_edit.c

@@ -1518,8 +1518,17 @@ void ED_screen_set(bContext *C, bScreen *sc)
 			WM_event_timer_sleep(wm, win, wt, true);
 		
 		ED_screen_exit(C, win, oldscreen);
-		oldscreen->animtimer = wt;
-		
+
+		/* Same scene, "transfer" playback to new screen. */
+		if (oldscene == sc->scene) {
+			sc->animtimer = wt;
+		}
+		/* Else, stop playback. */
+		else {
+			oldscreen->animtimer = wt;
+			ED_screen_animation_play(C, 0, 0);
+		}
+
 		win->screen = sc;
 		CTX_wm_window_set(C, win);  // stores C->wm.screen... hrmf