Hello!
One feature that would make this software even more incredible would be the ability to search your mindmap (including attachment text) for any string. This would allow users to easily reference any data even in a very large mindmap, and this would also make this software competitive with sites like Trello.
Regarding how the search should function: I think the search tools that treat each word (with space as a delimiter) as a separate string are the most helpful. For example, if I searched "raining cats and dogs," then the search would return any bubbles that contain "raining" OR "cats" OR "and" OR "dogs" - instead of insisting that all matches must have the exact same word order.