Move thread action to the right and show if available only

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

@@ -240,6 +240,8 @@ public class FragmentMessage extends Fragment {
                     db.attachment().liveAttachments(id).removeObservers(FragmentMessage.this);
                     db.attachment().liveAttachments(id).observe(FragmentMessage.this, attachmentsObserver);
 
+                    top_navigation.getMenu().findItem(R.id.action_thread).setVisible(message.count > 1);
+
                     MenuItem actionSeen = top_navigation.getMenu().findItem(R.id.action_seen);
                     actionSeen.setIcon(message.ui_seen
                             ? R.drawable.baseline_visibility_off_24

app/src/main/res/menu/action_view_top.xml

@@ -2,18 +2,18 @@
 <menu xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto">
 
-    <item
-        android:id="@+id/action_seen"
-        android:icon="@drawable/baseline_visibility_off_black_18"
-        android:title="@string/title_seen"
-        app:showAsAction="ifRoom" />
-
     <item
         android:id="@+id/action_thread"
         android:icon="@drawable/baseline_message_24"
         android:title="@string/title_thread"
         app:showAsAction="ifRoom" />
 
+    <item
+        android:id="@+id/action_seen"
+        android:icon="@drawable/baseline_visibility_off_black_18"
+        android:title="@string/title_seen"
+        app:showAsAction="ifRoom" />
+
     <item
         android:id="@+id/action_move"
         android:icon="@drawable/baseline_folder_24"

app/src/main/res/values/strings.xml

@@ -82,9 +82,9 @@
     <string name="title_subject_reply">Re: %1$s</string>
     <string name="title_subject_forward">Fwd: %1$s</string>
 
+    <string name="title_thread">Thread</string>
     <string name="title_seen">Read</string>
     <string name="title_unseen">Unread</string>
-    <string name="title_thread">Thread</string>
     <string name="title_move">Move</string>
     <string name="title_forward">Forward</string>
     <string name="title_reply_all">Reply to all</string>