I'm talking about yEd. If the app puts a border/container thing around the group, then that's what I'm talking about.
I think the grouping implementation could be more like e.g. an Adobe product like Illustrator or Photoshop, or pretty much any of the top 100 desktop publishing apps of the last 30 years. In the relatively infrequent case where we want a big border around the group, we can easily place it beneath. That is the exception, and if anything needs to be Googled to be learned, it should be that, not a basic task like how to ungroup.
What if I want to hide the folder border thing, but want to keep the grouping behavior (drag and drop as one, etc.)? We should be able to do this! But personally I think the border / container thing should be hidden by default. But don’t ask me, do a survey of your competitor’s users (not your own, because of ‘sunk cost fallacy’). As to how you would implement the activation of the visibility of the border / container, have you ever heard of 'context sensitivity'? If not, I would again point you to the two programs mentioned above - in short - the limited real estate that is the available panel / UI space at any given time is intelligently and sensitively responsive to the task at hand. These 'Clever Panels' are for me (for the moment) the ideal (presumably the most common tasks are prioritized), but a slightly less intuitive approach is also common (e.g. Microsoft Word), which is still worth mentioning, i.e. a right click on the object reveals it's properties / config / options. I don't see the harm in providing both solutions simultaneously where possible. At the moment, I would not feel comfortable using the group tool because it’s container / border thing is far too dominant for me.
Gestalt design principles exploit the brains innate facility for grouping by proximity alone. The border is seen as superfluous. These considerations, together with user research could help you to prioritize configuration: which are defaults and which need to be activated by a user action? It’s not an easy question, cause often people don’t know what they want until they’ve tried it. But at the very least, I think it’s good to somehow, provide a way to do a relatively basic task, even if it’s buried in a sub menu of a sub menu...