Fix long press on image thumbnail in detail view.

Allow long press to select inside select mode.

src/org/thoughtcrime/securesms/mediaoverview/MediaGalleryAllAdapter.java

@@ -283,7 +283,6 @@ final class MediaGalleryAllAdapter extends StickyHeaderGridAdapter {
       }
 
       thumbnailView.setImageResource(glideRequests, slide, false, false);
-
       thumbnailView.setOnClickListener(view -> itemClickListener.onMediaClicked(mediaRecord));
       thumbnailView.setOnLongClickListener(view -> onLongClick());
     }
@@ -466,6 +465,7 @@ final class MediaGalleryAllAdapter extends StickyHeaderGridAdapter {
 
       thumbnailView.setImageResource(glideRequests, slide, false, false);
       thumbnailView.setOnClickListener(view -> itemClickListener.onMediaClicked(mediaRecord));
+      thumbnailView.setOnLongClickListener(view -> onLongClick());
     }
 
     @Override

src/org/thoughtcrime/securesms/mediaoverview/MediaOverviewPageFragment.java

@@ -253,10 +253,10 @@ public final class MediaOverviewPageFragment extends Fragment
 
   @Override
   public void onMediaLongClicked(MediaDatabase.MediaRecord mediaRecord) {
-    if (actionMode == null) {
     ((MediaGalleryAllAdapter) recyclerView.getAdapter()).toggleSelection(mediaRecord);
     recyclerView.getAdapter().notifyDataSetChanged();
 
+    if (actionMode == null) {
       enterMultiSelect();
     }
   }