Start implementing multi-select and action modes. Needs testing...

OpenKeychain/src/main/res/layout/key_list_item.xml

@@ -5,11 +5,12 @@
 
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:minHeight="?android:attr/listPreferredItemHeight"
+    android:minHeight="?attr/listPreferredItemHeight"
     android:gravity="center_vertical"
     android:maxLines="1"
     android:orientation="horizontal"
     android:descendantFocusability="blocksDescendants"
+    android:background="@drawable/list_item_ripple"
     android:focusable="false">
 
     <LinearLayout