Confirm mark all as read

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

@@ -4402,6 +4402,11 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
     }
 
     private void onMenuMarkAllRead() {
+        new AlertDialog.Builder(getContext())
+                .setTitle(R.string.title_mark_all_read)
+                .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
                         Bundle args = new Bundle();
                         args.putString("type", type);
                         args.putLong("folder", folder);
@@ -4448,6 +4453,10 @@ public class FragmentMessages extends FragmentBase implements SharedPreferences.
                             }
                         }.execute(FragmentMessages.this, args, "message:read");
                     }
+                })
+                .setNegativeButton(android.R.string.cancel, null)
+                .show();
+    }
 
     private void onMenuSyncMore() {
         Bundle args = new Bundle();