Make bottom navigation actions invisible when unavailable

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

@@ -181,7 +181,7 @@ public class FragmentCompose extends Fragment {
         // Initialize
         grpReady.setVisibility(View.GONE);
         pbWait.setVisibility(View.VISIBLE);
-        bottom_navigation.getMenu().findItem(R.id.action_delete).setEnabled(id > 0);
+        bottom_navigation.getMenu().findItem(R.id.action_delete).setVisible(id > 0);
         bottom_navigation.setEnabled(false);
 
         DB.getInstance(getContext()).identity().liveIdentities(true).observe(getActivity(), new Observer<List<EntityIdentity>>() {

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

@@ -246,8 +246,8 @@ public class FragmentMessage extends Fragment {
                             : R.drawable.baseline_visibility_24);
                     actionSeen.setTitle(message.ui_seen ? R.string.title_unseen : R.string.title_seen);
 
-                    bottom_navigation.getMenu().findItem(R.id.action_spam).setEnabled(message.account != null);
-                    bottom_navigation.getMenu().findItem(R.id.action_archive).setEnabled(message.account != null);
+                    bottom_navigation.getMenu().findItem(R.id.action_spam).setVisible(message.account != null);
+                    bottom_navigation.getMenu().findItem(R.id.action_archive).setVisible(message.account != null);
                     tvBody.setText(message.body == null
                             ? null
                             : Html.fromHtml(HtmlHelper.sanitize(getContext(), message.body, false)));