Detach GalleryView layout manager when Activity onPause

app/src/main/java/com/hippo/ehviewer/ui/GalleryActivity.java

@@ -282,6 +282,24 @@ public class GalleryActivity extends TrackedActivity
         mSlider = null;
     }
 
+    @Override
+    protected void onPause() {
+        super.onPause();
+
+        if (null != mGalleryView) {
+            mGalleryView.pause();
+        }
+    }
+
+    @Override
+    protected void onResume() {
+        super.onResume();
+
+        if (null != mGalleryView) {
+            mGalleryView.resume();
+        }
+    }
+
     @Override
     public void onWindowFocusChanged(boolean hasFocus) {
         super.onWindowFocusChanged(hasFocus);