fix media preview in tablet mode

src/main/java/eu/siacs/conversations/ui/ConversationFragment.java

@@ -1865,6 +1865,8 @@ public class ConversationFragment extends XmppFragment implements EditMessage.Ke
         }
         updateChatState(this.conversation, msg);
         messageListAdapter.stopAudioPlayer();
+        mediaPreviewAdapter.clearPreviews();
+        toggleInputMethod();
     }
 
     public void reInit(Conversation conversation, Bundle extras) {

src/main/java/eu/siacs/conversations/ui/adapter/MediaPreviewAdapter.java

@@ -166,6 +166,10 @@ public class MediaPreviewAdapter extends RecyclerView.Adapter<MediaPreviewAdapte
         return mediaPreviews;
     }
 
+    public void clearPreviews() {
+        this.mediaPreviews.clear();
+    }
+
     class MediaPreviewViewHolder extends RecyclerView.ViewHolder {
 
         private final MediaPreviewBinding binding;