Allow clearing notes

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

@@ -6676,17 +6676,7 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
                 }
             });
 
-            return new AlertDialog.Builder(context)
-                    .setView(view)
-                    .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
-                        @Override
-                        public void onClick(DialogInterface dialog, int which) {
-                            Bundle args = new Bundle();
-                            args.putLong("id", id);
-                            args.putString("notes", etNotes.getText().toString());
-                            args.putInt("color", btnColor.getColor());
-
-                            new SimpleTask<Void>() {
+            final SimpleTask<Void> task = new SimpleTask<Void>() {
                 @Override
                 protected Void onExecute(Context context, Bundle args) {
                     long id = args.getLong("id");
@@ -6731,11 +6721,37 @@ public class AdapterMessage extends RecyclerView.Adapter<AdapterMessage.ViewHold
                 protected void onException(Bundle args, Throwable ex) {
                     Log.unexpectedError(getParentFragmentManager(), ex);
                 }
-                            }.execute(getContext(), getActivity(), args, "message:note");
+            };
+
+            AlertDialog.Builder builder = new AlertDialog.Builder(context)
+                    .setView(view)
+                    .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+                        @Override
+                        public void onClick(DialogInterface dialog, int which) {
+                            Bundle args = new Bundle();
+                            args.putLong("id", id);
+                            args.putString("notes", etNotes.getText().toString());
+                            args.putInt("color", btnColor.getColor());
+
+                            task.execute(getContext(), getActivity(), args, "message:note");
                         }
                     })
-                    .setNegativeButton(android.R.string.cancel, null)
-                    .create();
+                    .setNegativeButton(android.R.string.cancel, null);
+
+            if (!TextUtils.isEmpty(notes))
+                builder.setNeutralButton(R.string.title_reset, new DialogInterface.OnClickListener() {
+                    @Override
+                    public void onClick(DialogInterface dialog, int which) {
+                        Bundle args = new Bundle();
+                        args.putLong("id", id);
+                        args.putString("notes", "");
+                        args.putInt("color", Color.TRANSPARENT);
+
+                        task.execute(getContext(), getActivity(), args, "message:note");
+                    }
+                });
+
+            return builder.create();
         }
 
         @Override