Do you have plan to fix undo,redo problem?

[isscc]

I found Activiti-Designer is using graphiti framwork, while the model is non-EMF model。
So create feature and delete feature sometimes need implement custom undo/redo method。
But I don't see some custom feature implements 'ICustomUndoRedoFeature' in version 5.18.1.
So undo/redo function may have problem. example:

1. create a sequence flow between two node
2. undo create sequence flow
3. the sequence flow will not be created even if this sequence is delete
   Do you have plan to fix undo,redo problem?