Added multiple selection

app/src/main/java/eu/faircode/email/ItemDetailsLookupMessage.java

@@ -0,0 +1,29 @@
+package eu.faircode.email;
+
+import android.view.MotionEvent;
+import android.view.View;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.ItemDetailsLookup;
+import androidx.recyclerview.widget.RecyclerView;
+
+public class ItemDetailsLookupMessage extends ItemDetailsLookup<Long> {
+    private RecyclerView recyclerView;
+
+    ItemDetailsLookupMessage(RecyclerView recyclerView) {
+        this.recyclerView = recyclerView;
+    }
+
+    @Nullable
+    @Override
+    public ItemDetails<Long> getItemDetails(@NonNull MotionEvent motionEvent) {
+        View view = recyclerView.findChildViewUnder(motionEvent.getX(), motionEvent.getY());
+        if (view != null) {
+            RecyclerView.ViewHolder viewHolder = recyclerView.getChildViewHolder(view);
+            if (viewHolder instanceof AdapterMessage.ViewHolder)
+                return ((AdapterMessage.ViewHolder) viewHolder).getItemDetails(motionEvent);
+        }
+        return null;
+    }
+}