When tasks are moved to top or bottom, the app tokens are being rearranged.

The window token rearrangement is defered if an animation is
underway. Force a focus recomputation when the window tokens are finally
rearranged so that we have a valid focused window.

services/java/com/android/server/WindowManagerService.java

@@ -9629,6 +9629,10 @@ public class WindowManagerService extends IWindowManager.Stub
                     moveInputMethodWindowsIfNeededLocked(false);
                     wallpaperMayChange = true;
                     mLayoutNeeded = true;
+                    // Since the window list has been rebuilt, focus might
+                    // have to be recomputed since the actual order of windows
+                    // might have changed again.
+                    focusMayChange = true;
                 }
                 
                 int adjResult = 0;